Skip to main content

Full text of "Brunelleschi's dome : the story of the great cathedral in Florence"

See other formats




The Story of 

the Great Cathedral 

in Florence 


^wm tdt Xib\ai,ij of 



Ross King is the author of two novels, Domino 
and Ex-Libris, which have been translated into 
seven languages. He lives near Oxford. 

Digitized by the Internet Archive 
in 2010 


The Story of the Great Cathedral in Florence 



Published by Piinlico 2001 

6 8 10 9 7 

Copyright © Ross King 2000 

Ross King has asserted his right 

under the Copyright, Designs and Patents Act 1988 

to be identified as the author of this work 

This book is sold subject to the condition that it shall not, by way 

of trade or otherwise, be lent, resold, hired out, or otherwise 

circulated without the publisher's prior consent in any fomi 

of binding or cover other than that in which it is published 

and without a similar condition including this condition 

being imposed on the subsequent purchaser 

First published in Great Bntain by 

Chatto & Windus 2000 

Pimlico edition 2001 


Random House, 20 Vauxhall Bridge Road, 

London SWIV 2SA 

Random House Australia (Pty) Limited 

20 Alfred Street, Milsons Point, Sydney, 

New South Wales 2061, Australia 

Random House New Zealand Limited 
18 Poland Road, Glenfield, 
Auckland 10, New Zealand 

Random House (Pr\') Limited 
EnduHni, 5A Jubilee Road, Parktown 2193, South Africa 

Random House Group Limited Reg. No. 954009 

A CIP catalogue record for this book 
is available from the British Librar\' 

ISBN 0-7126-6480-7 

Papers used by Random House are natural, 

recyclable products made from wood grown in sustainable forests. 

The manufacturing processes conform to the environmental 

regulations of the country of origin 

Printed and bound in Great Britain by 
Biddies Ltd, Guildford 

For Mark Asquith and Anne-Marie Rigard 


My thanks to everyone who assisted with the research and writing of this 
book. I am indebted to Alta Macadam for reading the manuscript and 
sharing with me her encyclopaedic knowledge of Florence, and to Sir Jack 
Zunz for his expertise in structural engineering and his understanding of 
the finer points of Brunelleschi's technological achievement. A number of 
other people also read the manuscript in draft form and offered valuable 
advice: Mark Asquith, Ronald Jonkers, Sophie Oxenham, Anne-Marie 
Rigard and Amir Ramezani. For help with translations I am grateful to 
Cristiana Papi and to my sister Maureen King. Thanks also to Maureen 
for tracking down a number of important periodical articles that would 
otherwise have been inaccessible to me. Sarah Challis executed diagrams 
for the text, while Margaret Duffy and Richard Mabey provided 
information in response to my queries. During the course of my research I 
was assisted on numerous occasions by the staffs of the British Library, the 
Bodleian Library, the London Library and the Oxford University 
Engineering Science Library. 

I also wish to thank my editors, Rebecca Carter and Roger Cazalet, 
both of whom saved me from errors in presentation and infelicities of 
style; my agent, Christopher Sinclair-Stevenson, whose steadfast support 
for the project was vital at every stage; and my German editor, Karl-Heinz 
Bittel, whose support has likewise kept the book afloat. Finally, I must 
record my thanks to the two people to whom the book is dedicated, Mark 
Asquith and Anne-Marie Rigard. I will always be grateful for their 
hospitality in London and companionship in Florence, but above all for 
their constant friendship. 


1 A More Beautiful and Honourable Temple i 

2 The Goldsmith of San Giovanni 12 

3 The Treasure Hunters 22 

4 An Ass and a Babbler 33 

5 The Rivals 44 

6 Men Without Name or Family 51 

7 Some Unheard-of Machine 58 

8 The Chain of Stone 72 

9 The Tale o£ the Fat Carpenter 78 

10 The Pointed Fifth 83 

11 Bricks and Mortar 92 

12 Circle by Circle 102 

13 The Monster of the Arno no 

14 Debacle at Lucca 120 

15 From Bad to Worse 130 

16 Consecration 139 

17 The Lantern 143 

18 Ingenii Viri Philippi Brunelleschi 154 

19 The Nest of Delights 160 

NOTES 168 


INDEX 177 



Giovanni Battista Nelli: Section drawing of Santa Maria del Fiore. 5 

Bernardo Sansonc Sgrilli: Ground plan of Piazza di S. M. del Fiore. 5 

Giovanni Battista Clemente Nclli: Baptistery of San Giovanni. 15 

J. Buhlmann: Interior of Pantheon, Rome. (AKG) 29 

Taccola: Brunelleschi's ox-hoist, Biblioteca Nationale Centrale, Florence. 61 
Buonaccorso Ghiberti: Brunelleschi's ox-hoist, Biblioteca Nationale Centrale, 

Florence. 63 

Anonymous: Drawing of a spring operated clock, British Library. 67 
Buonaccorso Ghiberti: Vertical screw with triple turnhuckle and lewis holt inset, 

Biblioteca Nationale Centrale, Florence. 69 

Leonardo da Vinci: Drawing of Brunelleschi's 'castello', Biblioteca Ambrosiana. 70 
Antonio da Sangallo il Vecchio: Drawing of herring-bone brickwork, Gabinetto 

Disegni e Stampe degli Uffizi. 98 
Biagio d' Antonio: Archangels in a Fuscan Landscape, Bartolini-Salimbeni 

Collection. (Alinari) 105 
Girolamo Benivieni: Illustration of Dante's Hell from Dialogo di Antonio 

Manetti cittadino forentino circa al sito, forme e misure dello 'Inferno' di Dante 

Alighieri poeta excellentissimo, Florence, 1506. 109 
Taccola: Drawing of a column being shipped from a quarry, Biblioteca Nationale 

Centrale, Florence. 116 

Francesco di Giorgio: Drawing of a paddle-boat, British Museum Library. 117 
Buonaccorso Ghiberti: Brunelleschi's lantern hoist, Biblioteca Nationale Centrale, 

Florence. 147 

Brunelleschi's Death Mask, Museo dell'Opcra del Duomo. (© E. Battisti) 158 

Drawing of the dome being struck by lightning. {© Howard Saalman) 166 
Gherardo Mechini: Scaffolding for the lantern of S. M. del Fiore, Gabinetto 

Disegni e Stampe degli Uffizi. 166 

View of the dome. (AKG) 167 


Domenico di Michelino: Dante reading from the 'Divine Comedy', S. M. del Fiore. 

(Bridgeman Art Library) 
Italian School: Fhe 'Carta della Catena' showing a panorama of Florence, l^go, Museo di 

Firenzc Com'era. (Bridgeman Art Library) 
View of the belltower and cathedral. (Scala) 
Buttresses and ribs of the dome seen from above. (Scala) 
Interior of the dome. (Scala) 

The air space between the two shells of the dome. (Scala) 
View of the dome. (AKG) 

The author and publisher are grateful for permission to reproduce illustrations in 
this book, and to Sarah Challis and Eugenio Battisti for their diagrams. 

A More Beautiful and Honourable Temple 

ON THE NINETEENTH OF AUGUST 1418 a competition was 
announced in Florence, where the city's magnificent new 
cathedral, Santa Maria del Fiore, had been under construction 
for more than a century: 

Whoever desires to make any model or design for the vaulting of the main Dome of the 
Cathedral under construction by the Opera del Duomo —for armature, scaffold or other 
thing, or any lifting device pertaining to the construction and perfection of said cupola or 
vault — shall do so before the end of the month of September. If the model be used he 
shall be entitled to a payment of zoo gold Florins. 

Two hundred florins was a good deal of money — more than a skilled 
craftsman could earn in two years of work — and so the competition 
attracted the attention of carpenters, masons and cabinet-makers from all 
across Tuscany. They had six weeks to build their models, draw their 
designs, or simply make suggestions how the dome of the cathedral might 
be built. Their proposals were intended to solve a variety of problems, 
includmg how a temporary wooden support network could be constructed 
to hold the dome's masonry in place, and how sandstone and marble 
blocks each weighing several tons might be raised to its top. The Opera 
del Duomo — the office of works in charge of the cathedral — reassured all 

Brunelleschi's Dome 

prospective competitors that their efforts would receive *a friendly and 
trustworthy audience'. 

Already at work on the building site, which sprawled through the heart 
of Florence, were scores o{ other craftsmen: carters, bricklayers, lead- 
beaters, even cooks and men whose job it was to sell wine to the workers 
on their lunch breaks. From the piazza surrounding the cathedral the men 
could be seen carting bags of sand and lime, or else clambering about on 
wooden scaffolds and wickerwork platforms that rose above the 
neighbouring rooftops like a great, untidy bird's nest. Nearby, a forge for 
repairing their tools belched clouds of black smoke into the sky, and from 
dawn to dusk the air rang with the blows of the blacksmith's hammer and 
with the rumble of ox-carts and the shouting of orders. 

Florence in the early 1400s still retained a rural aspect. Wheatfields, 
orchards and vineyards could be found inside its walls, while flocks of 
sheep were driven bleating through the streets to the market near the 
Baptistery of San Giovanni. But the city also had a population of 50,000, 
roughly the same as London's, and the new cathedral was intended to 
reflect its importance as a large and powerful mercantile city. Florence had 
become one of the most prosperous cities in Europe. Much of its wealth 
came from the wool industry started by the Umiliati monks soon after 
their arrival in the city in 1239. Bales of English wool — the finest in the 
world — were brought from monasteries in the Cotswolds to be washed in 
the River Arno, combed, spun into yarn, woven on wooden looms, then 
dyed beautiful colours: vermilion, made from cinnabar gathered on the 
shores of the Red Sea, or a brilliant yellow procured from the crocuses 
growing in meadows near the hilltop town of San Gimignano. The result 
was the most expensive and most sought-after cloth in Europe. 

Because of this prosperity, Florence had undergone a building boom 
during the 1300s the like of which had not been seen in Italy since the time 
of the Ancient Romans. Quarries of golden-brown sandstone were opened 
inside the city walls; sand from the River Arno, dredged and filtered after 
every flood, was used in the making of mortar, and gravel was harvested 
from the riverbed to fill in the walls of the dozens of new buildings that 

A More Beautiful and Honourable Temple 

had begun springing up all over the city. These included churches, 
monasteries and private palaces, as well as monumental structures such as a 
new ring of defensive walls to protect the city from invaders. Standing 
twenty feet high and running five miles in circumference, these 
fortifications, not finished until 1340, took more than fifty years to build. 
An imposing new town hall, the Palazzo Vecchio, had also been 
constructed, complete with a bell tower that stood more than three 
hundred feet high. Another impressive tower was the cathedral's 280-foot 
campanile, with its bas-reliefs and multicoloured encrustations of marble. 
Designed by the painter Giotto, it had been completed in 1359, after more 
than two decades of work. 

Yet by 1418 what was by far the grandest building project in Florence 
had still to be completed. A replacement for the ancient and dilapidated 
church of Santa Reparata, the new cathedral of Santa Maria del Fiore was 
intended to be one of the largest in Christendom. Entire forests had been 
requisitioned to provide timber for it, and huge slabs o£ marble were bemg 
transported along the Arno on flotillas o{ boats. From the outset its 
construction had as much to do with civic pride as religious faith: the 
cathedral was to be built, the Commune of Florence had stipulated, with 
the greatest lavishness and magnificence possible, and once completed it 
was to be 'a more beautiful and honourable temple than any in any other 
party of Tuscany'. But it was clear that the builders faced major obstacles, 
and the closer the cathedral came to completion, the more difficult their 
task would become. 

The way forward should have been clear enough. For the past fifty years 
the south aisle of the unfinished cathedral had housed a 30-foot-long scale 
model of the structure, in effect an artist's impression of what the 
cathedral should look like once finished. The problem was that the model 
included an enormous dome — a dome that, if built, would be the highest 
and widest vault ever raised. And for fifty years it had been obvious that 
no one in Florence — or anywhere in Italy, for that matter — had any clear 
idea how to construct it. The unbuilt dome of Santa Maria del Fiore had 
therefore become the greatest architectural puzzle of the age. Many experts 

Bmnelleschi's Dome 

considered its erection an impossible feat. Even the original planners of the 
dome had been unable to advise how their project might be completed: 
they merely expressed a touching faith that at some point in the future 
God might provide a solution and that architects with a more advanced 
knowledge would be found. 

The foundation stone for the new cathedral had been laid in 1296. The 
designer and original architect was a master mason named Arnolfo di 
Cambio, the builder of both the Palazzo Vecchio and the city's massive 
new fortifications. Although Arnolfo died soon after construction began, 
the masons forged on, and over the next few decades a whole section of 
Florence was razed to make way for the new building. Santa Reparata and 
another ancient church, San Michele Visdomini, were both demolished 
and the inhabitants of the surrounding district were displaced from their 
homes. Not only the living were evicted: in order to open a piazza in front 
o{ the church, the bones of long-dead Florentines were exhumed from 
their graves surrounding the Baptister\' of San Giovanni, which stood a few 
feet to the west of the building site. In 1339 one of the streets south of the 
cathedral, the Corso degli Adamari (now the Via dei Calzaiuoli) was 
lowered so that the cathedral's height should appear even more impressive 
to anyone approaching from that direction. 

But as Santa Maria del Fiore grew steadily larger, Florence was 
shrinking. In the autumn of 1347 the Genoese fleet returned to Italy 
carrying in its holds not only spices from India but also the Asian black 
rat, carrier o£ the Black Death. As much as four-fifths of the population of 
Florence were to die over the next twelve months, so depopulating the city 
that Tartar and Circassian slaves were imported to ease the labour 
shortages. As late as 1355, therefore, nothing existed of the cathedral except 
for the fa<;ade and the walls of the nave. The interior of the church lay 
open to the elements, like a ruin, and the foundations for the unbuilt east 
end had been exposed for so long that one of the streets east of the 
cathedral was known as Lungo di Fondamcnti. or 'Along the Founda- 

Over the next decade, however, as the cit\' gradually recovered, work on 


■'-^^i' d-/m,'.A/im.' .'/Ty/,/.^; ./;//,. ^//Jf, J^,^., AB. Jf//,i^p,/u //. 


I. A section drawing of Santa Maria del Fiore by Giovanni Battista Nelli. 

2. A ground plan of the cathedral showing the three tribunes, with their chapels, 
around the dome's octagon. On the right, in the piazza, is the Baptistery. 

Brunelleschi's Dome 

the cathedral accelerated, and by 1366 the nave had been vaulted and the 
east end of the church, which included the dome, was ready to be planned. 
Arnolfo di Cambio had undoubtedly envisioned a dome for the church, 
but there is no surviving evidence of his original design: some time in the 
fourteenth century his model o{ the cathedral collapsed under its own 
weight — an ominous sign — and was subsequently lost or demolished. But 
excavations during the 1970s uncovered the foundations for a dome that 
was intended to have a span of 62 hraccia, or 119 feet (a Florentine hraccia 
being 23 inches, roughly the length of a man's arm). With this diameter 
the cupola of Santa Maria del Fiore would have exceeded by some twelve 
feet the span of the dome of the world's most spectacular church, Santa 
Sophia in Constantinople, which had been built 900 years earlier by the 
Emperor Justinian. 

Since the 1330s responsibility for building and funding the cathedral had 
been in the hands of Florence's largest, wealthiest and most powerful 
guild, the Wool Merchants, who administered the Opera del Duomo. 
None o^ the wardens running the Opera knew the first thing about 
building churches: their business was wool, not architecture. It therefore 
fell to them to appoint someone who did understand the craft, an 
architect-in-chief, or capotnaestro, who would create the models and designs 
for the cathedral and also deal with the masons and other builders 
involved in the actual construction. In 1366, as planning reached its crucial 
stage, the capomaestro of Santa Maria del Fiore was a man named Giovanni 
di Lapo Ghini. At the request of the Opera, Giovanni began building a 
model for the cathedral's dome. But the wardens also ordered a second 
model from a group of artists and masons led by another master mason, 
Neri di Fioravanti.^ The fate of Santa Maria del Fiore was about to 
undergo a radical change. 

Competition between architects was an old and honoured custom. 
Patrons had been making architects compete against one another for their 
commissions since at least 448 EC, when the Council of Athens held a 
public competition for the war memorial it planned to build on the 
Acropolis. Under these circumstances, it was normal practice for architects 

A More Beautiful and Honourable Temple 

to produce models as a means of convmcmg patrons or panels of judges ot 
the virtues of their particular designs. Made trom wood, stone, brick or 
even clav or wax, such models allowed the patrons to visualise the 
cUmensions and decorations of the end product much more easilv than 
would a diagram executed on parchment. Thev were often large and highly 
detailed — so large, in fact, that m manv cases patrons could walk inside to 
inspect the interior. The brick-and-plaster model for San Petronio m 
Bologna, for example, built in 1390, was 59 feet long and, therefore, a good 
deal larger than most houses. 

Giovanni di Lapo Ghini set about building a model that was tairlv 
traditional m srvie. He planned a rvpicallv Gothic structure with thin 
walls, tall wmdows and. to support the dome, external buttresses of the 
sort adorning so manv of the churches built m France during the previous 
centun". Buttresses were one of the prime structural features ot Gothic 
architecture: bv accommodating the thrust of the vaults transterred to 
them from strategic points thev allowed for walls pierced bv a multitude of 
windows to rise to spectacular heights, fillmg the church with heavenlv 
light — the aspiration of all Gothic builders. 

Xen di Fioravanti and his group rejected the external supports 
proposed bv Giovanni di Lapo Ghini. however, and offered a different 
approach to the structure of the dome. Flving buttresses were rare m Italv, 
where architects regarded them as uglv and awkward makeshifts."" But 
Nen's reasons for rejectmg them were probablv political as much as 
aesthetic or structural in that thev smacked of the architecture of 
Florence s traditional enemies: Germanv. France and Milan. How the 
German barbarians, the Goths, had covered Europe with their clumsv and 
disproportional edifices would later become a popular theme with writers 
of the Italian Renaissance. 

But if no flving buttresses were to be built, how was the dome to be 
supported: Neri di Fioravanti, the prmcipal master mason in Florence, had 
extensive experience m vaulting, the most dangerous and difficult 
architectural manoeuvre. He was the man responsible for erectmg the 
enormous 60-foot-wide vaults over the great hall of the Bargello as well as 

Brunelleschi's Dome 

the arches of the new Ponte Vecchio after the old bridge was swept away 
by a flood in 1333. But his plan for the dome of Santa Maria del Fiore was 
far more ambitious and largely untested: he believed the dome could be 
prevented from buckling under its own weight not by means of external 
buttresses but by the incorporation of a series of stone or wooden chains 
that would run round the circumference, encircling the dome at the points 
of possible rupture in the same way that an iron hoop contains the staves 
of a barrel. All of the lines of stress would therefore be absorbed by the 
structure itself without being channelled to the ground by means of 
external buttresses. Unlike buttresses, moreover, these circumferential 
rings, buried in the dome's masonry, would be invisible. And it was this 
vision of a massive dome that seemed to rise heavenwards without any 
visible means of support that for the next half-centur\' would both inspire 
and frustrate everyone involved with the project. 

The wardens in the Opera del Duomo did not decide between the two 
models without a good deal of debate. At first Neri and his group seemed 
to win the day, but Giovanni succeeded in raising questions about the 
stability of their design. His doubts illustrate a fear that haunted architects 
in the Middle Ages. Today a patron who hires an engineer takes it for 
granted that the end product will stand, even through earthquakes and 
hurricanes. But in the Middle Ages and the Renaissance, before the science 
of statics was developed, a patron enjoyed no such assurance, and it was 
not uncommon for buildings to fall down soon after completion, or even 
during the building process itself. The bell towers in both Pisa and 
Bologna began to lean while still under construction because of subsidence 
in the underlying soil, while the vaults in the cathedrals at both Beauvais 
and Troyes collapsed a relatively short time after being raised. The 
superstitious attributed these failures to supernatural causes, but to the 
more knowledgeable the real culprits were the architects and builders who 
had made fundamental (though imperfectly understood) errors in design. 

In the end Giovanni's concerns led the wardens to stipulate that, 
although Neri's model would be adopted, the pillars that supported the 
dome should be enlarged. But enlarging the pillars would create perhaps 

A More Beautiful and Honourable Temple 

even greater problems. Their dimensions were directly related to those of 
the octagonal tribune, whose perimeter they would form. The foundations 
for an octagon of 62 hraccia had already been begun: would this 
groundwork have to be undone? Even more serious, the diameter of the 
tribune could not be enlarged without a corresponding increase in the span 
of the cupola. Was it possible to build a dome with a span even larger 
than 62 hraccia, still without the use of any visible supports? 

These questions were addressed at the meeting in August 1367 in which 
the wardens opted for a dome that would be 10 hraccia wider than the one 
previously planned. Three months later, in keeping with Florentine 
democracy — and also, perhaps, in keeping with a desire on the part of the 
wardens to spread the blame as widely as possible — the plan was endorsed 
by a referendum of Florence's citizens. 

The decision to adopt Neri di Fioravanti's design represents a 
remarkable leap of faith. No dome approaching this span had been built 
since Antiquity, and with a mean diameter of 143 feet and 6 inches it 
would exceed that of even the Roman Pantheon, which for over a 
thousand years had been the world's largest dome by far. And the cupola 
of Santa Maria del Fiore would not only be the widest vault ever built: it 
would also be the highest. The walls of the cathedral were already 140 feet 
high, above which a tambour (or drum) on which the dome was to rest 
would rise another 30 feet. The purpose of this tambour was to elevate the 
dome — to serve, in effect, as a pedestal, raising the dome even higher 
above the city. Vaulting for the cupola would therefore begin at an 
incredible height of 170 feet, much higher than any of the Gothic vaults 
built in France during the thirteenth century. Indeed, the highest Gothic 
vault ever constructed, in the Cathedral of Saint-Pierre at Beauvais, began 
at just under 126 feet and rose to a maximum height of 157 feet, still a good 
13 feet below where the vaulting for the dome of Santa Maria del Fiore was 
to begin. And the choir at Beauvais spanned only 51 feet in contrast to the 
143 feet proposed for the cupola in Florence. The fact that the main vaults 
of the choir in Saint-Pierre had collapsed in 1284, little more than a decade 
after completion, cannot have eased the minds of the sceptics, especially 

Brunelleschi's Dome 

since the architects at Beauvais had made use of both iron tie rods and 
flying buttresses, the expedients so boldly rejected by the committee of 
artists and masons. 

Despite all the challenges it presented, Neri di Fioravanti's model set 
the basic form for the dome o{ Santa Maria del Fiore as it would 
ultimately be constructed. Intriguingly, it was to consist of not one but two 
domes, with one shell fitting inside the other. This type of structure was 
rare, though not unique, in Western Europe.^ Developed during the 
medieval period in Persia, it had become a characteristic feature of Islamic 
mosques and mausoleums. In such structures a tall outer shell was 
intended to give impressive height to the building, while the shallower 
inner one — which partially supported the outer dome — was more suited 
to the interior proportions. The outer dome also shielded the inner one 
from the elements, serving as a weathering skin. 

Besides the double shell, the other special feature of Neri's dome was its 
particular shape. Unlike most previous cupolas, including the Pantheon, 
that of Santa Maria del Fiore was to be pointed rather than hemispherical 
in profile. That is, instead of describing a semicircle, its sides would curve 
up towards a point in the same way that Gothic arches do. This shape was 
known as a quinto acuto or 'pointed fifth'. In technical terms the dome was 
to be an octagonal cloister-vault composed of four interpenetrating barrel 
vaults. This complex structure was to create unforeseen problems for the 
men who began to build it fifty years later, and its construction would call 
for ingenious solutions. 

Neri's model of the dome became an object of veneration in Florence. 
Standing 15 feet high and 30 feet long, it was displayed like a reliquary or 
shrine in one of the side aisles of the growing cathedral. Every year the 
cathedral's architects and wardens were obliged to place their hands on a 
copy of the Bible and swear an oath that they would build the church exactly 
as the model portrayed. Many aspiring carpenters and masons must also have 
walked past it on their way in and out of the cathedral, contemplating the 
problems of the dome's construction and dreaming of their solution. Thus 
when the competition to solve these difficulties was announced m 


A More Beautiful and Honourable Temple 

the summer of 141 8, more than a dozen models were submitted to the 
Opera by various hopefuls, some by craftsmen from as far away as Pisa 
and Siena. 

However, of the many plans submitted, only one — a model that offered 
a magnificently daring and unorthodox solution to the problem of vaultmg 
such a large space — appeared to show much promise. This model, made 
of brick, was built not by a carpenter or mason but by a man who would 
make it his life's work to solve the puzzles of the dome's construction: a 
goldsmith and clockmaker named Filippo Brunelleschi. 


The Goldsmith of San Giovanni 

IN 1418 FILIPPO BRUNELLESCHI -or 'Pippo', as he was known to 
everyone — was forty-one years old. He lived in the San Giovanni 
district of Florence, just west of the cathedral, in a large house he had 
inherited from his father, a prosperous and well-travelled notary named 
Ser Brunellesco di Lippo Lappi. Ser Brunellesco originally intended his son 
to follow in his footsteps, but Filippo had scant interest in a career as a 
civil servant, showing instead, from a young age, an uncanny talent for 
solving mechanical problems. No doubt his interest in machines had been 
sparked by the sight of the half-built cathedral that stood a short walk 
from the family home. Growing up in the shadow of Santa Maria del 
Fiore he would have seen in daily operation the treadwheel hoists and 
cranes that had been designed to raise blocks of marble and sandstone to 
the top of the building. And the mystery of how to build the dome was 
probably a topic of conversation in the family home: Ser Brunellesco 
possessed some knowledge of the subject, having been one of the citizens 
who in the referendum of 1367 had voted for the bold design of Neri di 

Although disappointed by his son's lack of desire to become a notary, 
Ser Brunellesco respected the boy's wishes, and when he was fifteen Filippo 
was apprenticed in the workshop of a family friend, a goldsmith named 


The Goldsmith of San Giovanni 

Benincasa Lotti. An apprenticeship with a goldsmith was a wise and logical 
choice for a boy showing mechanical ingenuity. Goldsmiths were the 
princes among the artisans of the Middle Ages, with a large scope to 
explore their numerous and varied talents. They could decorate a 
manuscript with gold leaf, set precious stones, cast metals, work with 
enamel, engrave silver and fashion anything from a gold button to a shrine, 
reliquary or tomb. It is no coincidence that the sculptors Andrea Orcagna, 
Luca della Robbia and Donatello, as well as the painters Paolo Uccello, 
Andrea del Verrocchio, Leonardo da Vinci and Benozzo Gozzoli — some 
of the brightest stars m a remarkable constellation of Florentine artists and 
craftsmen — had all originally trained in the workshops of goldsmiths. 

Despite its prestige, goldsmithing was not the most wholesome of 
professions. The large furnaces that were needed to melt gold, copper and 
bronze had to burn for days on end, even in the heat of summer, polluting 
the air with smoke and brmging the danger of explosions and fire. 
Noxious substances such as sulphur and lead were used to engrave silver, 
and the clay moulds in which metals were cast required supplies of both 
cow dung and charred ox-horn. Worse still, the workshops of most 
goldsmiths were found in Florence's most notorious slum, Santa Croce, a 
marshy and flood-prone area on the north bank of the Arno. This was the 
workers' district, home to dyers, wool-combers and prostitutes, all of 
whom lived and worked in a clutter of ramshackle wooden houses. 

Filippo thrived in this environment, however, quickly mastering the skill 
of mounting gems and the complex techniques of niello (engraving on 
silver) and embossing. At this time he also began studying the science of 
motion, and, in particular, weights, wheels and gears. The immediate fruits 
of these investigations were a number of clocks, one of which is even said 
to have included an alarm bell, makmg it one of the first alarm clocks ever 
invented. This clever device — of which, unfortunately, no evidence 
survives — appears to have been the first of his many stunning technical 

Filippo matriculated as a master goldsmith in 1398, at the age of twenty- 
one, then rose to city-wide prominence three years later during a 


Brunelleschi's Dome 

competition that, for its intense public interest, rivalled the one between 
Giovanni di Lapo Ghini and Neri di Fioravanti twenty-five years earlier. 
This was the famous competition for the bronze doors of the Baptistery of 
San Giovanni. 

This competition — which would play a pivotal role in Filippo's career 
— came about because of an outbreak of plague. The Black Death was a 
faithful visitor to Florence. It arrived, on average, once every ten years, 
always in the summer. After the horrors of 1348, there were further 
outbreaks, less severe, in 1363, 1374, 1383 and 1390. Various remedies were 
invented to drive it away. Church bells were violently rung, firearms 
discharged into the air, and the portrait of the Virgin from the church at 
nearby Impruneta — an image with miraculous powers that was said to 
have been painted by St Luke — was borne in procession through the 
streets. Those rich enough escaped into the country. Those who stayed 
behind burned wormwood, juniper and lavender in their hearths. Ox-horn 
and lumps of sulphur were also burned, because stenches were considered 
equally effective in clearing the air. So intense were these fumigations that 
sparrows would fall dead from the rooftops. 

One of the worst outbreaks occurred in the summer of 1400, when as 
many as 11,000 Florentines died — that is, just over one person in five. The 
following year, in order to appease the wrathful deity, the Guild of Cloth 
Merchants decided to sponsor a new set of bronze doors for San 
Giovanni. The Baptistery, at whose font every child in Florence was 
baptised, had long been one of the city's most venerated buildings. An 
octagonal, marble-encrusted, domed structure standing a few yards to the 
west of the rising hulk of the new cathedral, it was believed, erroneously, 
to be a Temple of Mars constructed by Julius Caesar to celebrate the 
Roman victory over the nearby town of Fiesole (when in fact it was built 
much later, probably in the seventh century AD). Between 1330 and 1336 the 
sculptor Andrea Pisano, later one of the cathedral's capomaestri, had cast 
bronze doors to ornament it: twenty panels showing scenes from the life 
of John the Baptist, the patron saint of Florence. But no further work had 


The Goldsmith of San Giovanni 

3. The Baptistery of San Giovanni. 

since been done to beautify the Baptistery, and Pisano's doors had 
themselves fallen into disrepair. 

Filippo was in Pistoia in 1401, having left Florence because of the 
plague. There he had been working in collaboration with several other 
artists on an altar in the cathedral — a prestigious commission — but he 
returned to Florence immediately upon hearing of the competition. 
Thirty-four judges were selected from among Florence's numerous artists 
and sculptors, along with various worthy citizens, including the wealthiest 
man in Florence, the banker Giovanni di Bicci de' Medici. These judges 
were charged with choosing the winner from among seven goldsmiths and 
sculptors, all of them Tuscans. 

The plague was not the only threat to Florence at this particular time. 
No sooner had the pestilence abated than a new danger, potentially worse, 
hove into view, with serious repercussions for, among other things, Santa 
Maria del Fiore. Work on the new cathedral had been moving on apace. 


Brunelleschi's Dome 

The great arches over the main pillars that would support the cupola had 
been started in 1397 and the chapels on three sides of the octagon were in 
the process of being vaulted. The Piazza dell'Opera, a triangular space to 
the east of the cathedral, had been laid out and paved, and a new building 
had been built to house the Opera del Duomo. Early in 1401, however, this 
activity abruptly ceased when the Duomo's masons were conscripted into 
service fortifying the walls of Castellina in Chianti, a small town on the 
road to Siena. Soon afterwards the Signoria, the executive body of the 
Republic, hastily ordered them to fortify those of two other towns, 
Malmantile and Lastra a Signa, both on the road to Pisa. 

The reason for this sudden flurry of building was a threat from the 
north: Giangaleazzo Visconti, the Duke of Milan, against whom the 
Florentines had fought a war ten years earlier. Giangaleazzo was a ginger- 
bearded tyrant, cruel and ambitious, whose coat of arms was suitably 
grisly: a coiled viper crushing in its jaws a tiny, struggling man. His 
autocratic rule differed drastically from the 'democracy' of Florence, which 
fulfilled Aristotle's criterion for an ideal republic in that it elected its rulers 
(albeit with a narrow franchise) to short terms in office. In 1385 
Giangaleazzo had seized power in Milan by imprisoning and then 
poisoning his uncle, Bemabo Visconti, who also happened to be his 
father-in-law. To befit his new status, Giangaleazzo had bribed the 
Emperor Wenceslas IV to grant him the title of Duke of Milan. He had 
also begun work on a new cathedral in Milan, an enormous Gothic 
structure complete with pinnacles and flying buttresses — precisely the sort 
of architecture to which Neri di Fioravanti and his group had objected. 

It was this old enemy, then, whose shadow now fell over Florence. Not 
content with his power in northern Italy, Giangaleazzo was proposing to 
unite the entire peninsula under his rule. Pisa, Siena and Perugia had 
already been subdued, and by 1401 only Florence stood between hmi and 
lordship of all northern and central Italy. Florence was politically and 
geographically isolated, cut off from the seaports of Pisa and Piombino. 
Under siege from Giangaleazzo, her trade came to a standstill and famine 
threatened. The Milanese tyrant even prevented Florence from importing 


The Goldsmith of San Giovanni 

supphes of the wire that was used to make instruments for cardmg wool. 
As his troops moved on Florence, the historic rights of the Republic 
looked doomed. 

It was against this background of urgency and crisis that the 
competition for the second set of bronze doors was played out. The rules 
of the competition were simple. Each of the candidates was given four 
sheets of bronze, weighing seventy-five pounds in all, and ordered to 
execute a scene based on an identical subject: Abraham's sacrifice of Isaac 
as described in Genesis 22:2—13. This story is traditionally said to prefigure 
the crucifixion of Christ, but to the Guild of Cloth Merchants, with 
Florence 'miraculously' delivered from the plague and with Giangaleazzo's 
armies fast approaching, more immediate analogies may have suggested 
themselves in this tale of sudden salvation from mortal threat. The 
competitors were given one year to complete their trial panels, which were 
to be some 17 inches high by 13 inches wide. 

A year may seem like a long time to execute such a relatively small 
work, but casting in bronze was a delicate operation demanding a high 
degree of skill. The first step m the process was to model the figure 
roughly in carefully seasoned clay over which, once the clay had dried, a 
coating of wax was laid. After the wax had been carved into the shape of 
the desired statue or relief — work of extreme sculptural precision — a new 
layer was laid over it: a combination of burnt ox-horn, iron filings and cow 
dung were mixed together with water, worked into a paste and spread over 
the wax-coated model with a brush of hog sables. Several layers of soft 
clay were then applied, each of which was allowed to dry before its 
successor was overspread. The result was a shapeless mass bound together 
with iron hoops — the lumpy chrysalis from which the bronze statue was 
to emerge. 

This creation was placed in a kiln and baked until the clay hardened 
and the layer of wax, as it melted, oozed through small vent holes made 
for that purpose, usually at the base. A hollow was thereby left into which 
bronze, melted in a furnace, was poured. The final step in the process was 
to break away the shapeless husk of baked clay and expose the bronze 


Brunelleschi's Dome 

figure, which could then be chiselled, engraved, polished and, if necessary, 
gilded. So fraught with opportunities for mishap was the whole process 
that, in later years, Michelangelo would request a Mass to be said 
whenever he began pouring a bronze statue. 

The trial pieces were completed and the judgement commenced in 1402, 
as Milanese troops displaying Giangaleazzo's gruesome insignia camped 
outside the gates of Florence. The prestigious commission would almost 
certainly make the victor's reputation. Of the original seven competitors, 
only two were considered worthy of the prize. Filippo Brunelleschi found 
himself pitted against another young, unknown goldsmith. And so began a 
lifelong professional rivalry. 

Lorenzo Ghiberti was not the most auspicious contender for such a major 
commission as the Baptistery doors. Only twenty-four years old and with 
no major works to his credit, he was a member of neither the goldsmiths' 
nor the sculptors' guilds. Worse still, he was of dubious paternity. 
Officially the son of a dissolute man named Cione Buonaccorso, he was 
rumoured to be the illegitimate child of a goldsmith, Bartoluccio Ghiberti, 
who was now his stepfather.^ He had apprenticed in Bartoluccio's 
workshop, assisting in the manufacture of earrings, buttons and various 
other staples of the goldsmith's trade — hardly tasks on the scale of the 
Baptistery doors. When plague broke out in 1400, Lorenzo had left for the 
healthier climate of Rimini, on the Adriatic coast, where he had worked 
not as a goldsmith but as a painter of murals. He returned to Florence a 
year later, on the urging of Bartoluccio, who assured him that if he won 
the commission for the Baptistery doors he need never make another 

The two finalists in the competition could not have approached their 
labours more differently. Lorenzo proved the more cunning tactician, 
canvassing widely for advice from other artists and sculptors, many of 
whom happened to be on the jury. Summoned into Bartoluccio's 
workshop in Santa Croce, they were asked for their opinions of the wax 
model which, no matter how carefully carved, Lorenzo was always willing 


The Goldsmith of San Giovanni 

to melt and reshape according to their criticisms. Advice was even 
soliticited from perfect strangers, the dyers and wool-combers of Santa 
Croce, who were beckoned into the shop as they passed on their way to 
work. He also made good use of Bartoluccio, who polished the finished 
work for him. 

Filippo, on the other hand, worked in isolation. Secrecy and individual 
effort were to be two hallmarks of his working habits over the next forty 
years. Later, whether making architectural models or specialised inventions 
such as hoists and boats, he insisted on his own solitary authorship, never 
committing his ideas to paper, or, if he did, only in cipher. He worked 
either alone or with one or two trusted disciples, always fearful that some 
unworthy soul would bungle his plans or attempt to steal the credit for 
them — a nightmare that was later to come true. 

In the end, the judges as well as the people of Florence were divided 
between the merits of the two bronze reliefs — a division that persists 
among art historians to this day. Filippo's panel is the more dramatic of 
the two, portraying both Abraham and the angel in histrionic and even 
violent poses above the contorting figure of Isaac. Lorenzo's figures, on the 
other hand, appear more graceful and elegant, and his panel was also 
technically more accomplished inasmuch as it used less bronze and was 
cast in a single piece. Visitors to Florence can make up their own minds 
about their respective virtues because the two panels are now preserved in 
the Museo Nazionale del Bargello. What became of the unsuccessful five 
is not known. They may well have been melted down during one of 
Florence's numerous wars — always a danger with bronze. The sixteenth- 
century Florentine antiquarian and collector Francisco Albertini recom- 
mended that goldsmiths who desired immortality should never cast their 
bronzes in a thickness greater than a knife's edge, because that way they 
would not be melted down for the casting of cannons. It was all too easy 
to turn bronze into gun-metal; one had only to add more tin — double the 
amount used to make bronze — to the alloy. Many of Lorenzo's later 
pieces appear to have met this fate. 

Two conflicting accounts exist of how the thirty-four judges arrived at 


Brunelleschi's Dome 

their final decision. One is courtesy of Lorenzo himself in his 
autobiography, the Commentarii; the other comes from Filippo's first 
biographer, Antonio di Tuccio Manetti, who, though not born until 1423, 
claims to have known his subject personally. Neither author is especially 
disinterested. Lorenzo asserts, with no trace of modesty, that he won the 
victor's palm 'without a single dissentmg voice', whereas in his Life of 
Brunelleschi, written in the 1480s, Manetti relates a more complicated tale in 
which the judges, unable to decide between the two pieces, reached a 
compromise and awarded the commission jointly to both men, who were 
henceforth to work in collaboration. This is not implausible given the size 
of the project and the relative inexperience of the two young goldsmiths. 
But Filippo, in Manetti's account, refused to work with Lorenzo, 
demanding that he alone be given charge of the work. This too sounds 
plausible considering that Filippo's arrogant self-confidence, irascibility 
and stubborn unwillingness to work with others is a theme that repeats 
itself throughout his life. 

According to Manetti, Filippo withdrew from the competition when his 
demand for complete control was refused, leaving the project in the hands 
of his rival. From that moment, he renounced sculpture — he would never 
again work in bronze — and quit Florence for Rome. F4ere he lived 
intermittently for the next fifteen years, making clocks and setting gems to 
support himself while he studied the crumbling ruins of ancient Rome. 
Lorenzo meanwhile was to spend the next twenty-two years at work on the 
bronze doors, which ultimately weighed ten tons and are acknowledged to 
be among the great masterpieces of Florentine art. 

And what of Giangaleazzo Visconti? As the Milanese armies besieged 
Florence in the summer of 1402, a holy hermit in the Tuscan countryside 
prophesied that the tyrant would die before the year was out. As it 
transpired, the prophecy was fulfilled with several months to spare. In the 
middle of August, in the sweltering Tuscan heat, just when Florence 
seemed within his grasp, Giangaleazzo fell ill with a fever, lingered for 
several weeks, then expired at the beginning of September aged fifty-two. 
Shortly thereafter the siege was lifted. The Milanese troops disbanded and 


The Goldsmith of San Giovanni 

the blockade was at an end. Florence had been spared and the greatest 
century in the history- of the Republic - what Voltaire caUs one o£ the 
greatest eras in the history of the world - was ready to commence. 


The Treasure Hunters 

ACAPITOLIUM, A FORUM, a Temple of Mars, an amphitheatre, 
an aqueduct, an equestrian statue o{ Mars on the Ponte Vecchio, 
Roman baths, assorted walls and towers, to say nothmg of the 
catacombs (^burelle^ which now served as a prison and, less officially, as 
hide-outs for prostitutes — the citizens of Florence saw ancient Roman 
ruins wherever they looked in their city. 

Or so they believed. The fact is that Florence was not especially rich in 
Roman remains. Many so-called Roman structures — the Baptistery, for 
example — actually dated from a much later and more modest era. 
Nevertheless these observations, however misguided, enjoyed a long and 
distinguished pedigree, for the historians of Florence were forever 
inventing spurious links between their city and ancient Rome. The Chronica 
de origine civitatis, an early history written in about 1200, claimed that the city 
was founded by Julius Caesar. A century later, in his Convivio, no less an 
authority than Dante called Florence 'that beautiful and famous daughter 
of Rome'. The humanist philosopher Leonardo Bruni agreed with this 
proud lineage but identified the founder not as Julius Caesar — an 
imperialist tyrant uncomfortably reminiscent of Giangaleazzo Visconti — 
but rather as Lucius Cornelius Sulla, who established the city some twenty 
years before Caesar's reign, during the height of the Roman Republic. 


The Treasure Hunters 

This conviction was given support in 1403 when relics and documents 
supposedly proving the case were discovered in the church of SS. Apostoli. 

Thus when Filippo set off for Rome some time after the end of the 
competition for the Baptistery doors, patriotic arguments about the 
Roman origins of the Florentine republic — arguments all the more 
strident during the years of the Visconti threat — would have been ringing 
in his ears. Yet in the early 1400s the Eternal City must have been, in most 
respects, a wretchedly uninspiring sight, a parent that the Florentines may 
well have wished to disown. A million people had dwelt in Rome during 
the height of the Empire, but now the city's population was less than that 
of Florence. The Black Death of 1348 had reduced numbers to zo,ooo, 
from which, over the next fifty years, they rose only slightly. Rome had 
shrunk into a tiny area inside its ancient walls, retreating from the seven 
hills to huddle among a few streets on the bank of the Tiber across from 
St Peter's, whose walls were in danger of collapse. Foxes and beggars 
roamed the filthy streets. Livestock grazed in the Forum, now known as // 
Campo Vaccino, or 'the Field of Cows'. Other monuments had suffered even 
worse fates. The Temple of Jupiter was a dunghill and both the Theatre of 
Pompey and the Mausoleum of Augustus had become quarries from 
which the ancient masonry was scavenged, some of it for buildings as far 
away as Westminster Abbey. Many ancient statues lay in shards, half- 
buried, while others had been burned in kilns to make quicklime or else 
fertiliser for the feeble crops. Still others were mangers for asses and oxen. 
The funerary monument of Agrippina the Elder, the mother of Caligula, 
had been turned into a measure for grain and salt. 

Rome was a dangerous and unappealing place. There were earthquakes, 
fevers and endless wars, the latest of which, the War of the Eight Saints, 
witnessed English mercenaries laying waste to the city. There was no trade 
or industry apart from the pilgrims who arrived from all over Europe, 
clutching copies of Mirabilia urbis romae ('The Wonders of Rome'), which 
told them which relics to see during their stay. This guidebook directed 
them to such holy sights as the finger bone of St Thomas in Santa Croce 
in Gerusalemme, the arm of St Anne and the head of the Samaritan 


Brunelleschi's Dome 

woman converted by Christ in San Paolo fuori le Mura, or the crib of the 
infant Saviour in Santa Maria Maggiore. There was a hucksterish 
atmosphere to the cit\': pardoners sold indulgences from stalls in the street, 
and churches advertised confessions that were supposedly good for a 
remission o{ infernal torture for a grand total of S,ooo years. 

The Mirahilia virhis romae did not direct the attention of the pilgrims to 
the Roman remains that surrounded them. To such pious Christians these 
ancient ruins were so much heathen idolatry'. Worse, they were stained 
with the blood of Christian mart\TS. The Baths of Diocletian, for example, 
were built with the forced labour of early Christians, many of whom had 
died during the construction. Antique images that had survived a 
millennium of earthquakes, erosion and neglect were therefore deliberately 
trampled underfoot, spat on, or thrown to the ground and smashed to 

Nevertheless, some of the old pagan glory of Rome persisted despite 
this new breed of Vandal. The high road from the south, the Via Appia, 
expertly paved with basalt blocks fitted together without mortar, was an 
architectural marvel in itself, cutting straight as an arrow through 
mountains, marshes and valleys. Of still more interest were the 300,000 
sepulchres that still lined the road for miles, the products of an ancient law 
that had prevented anyone except the Vestal Virgins and the Emperors 
from being buried within the walls of Rome. Or one could see the broken 
arches of aqueducts such as the Acqua Claudia. At 43 miles long, and with 
arches 100 feet in height, this structure was a testament not only to the 
fresh drinking water enjoyed by the ancient Romans (in comparison with 
their descendants, who took their water from the tainted, foul-smelling 
Tiber) but also to their remarkable engineering skills. Some modern-day 
Romans were even ignorant of its purpose, believing it to have been used 
to import olive oil from Naples. 

Filippo arrived in this squalid, crumbling city with the talented young 
Florentine sculptor Donatello, then an adolescent. It was an association 
that, despite some periods of turbulence, would endure for many years. 
The pair were well-matched given that Donatello was, if anything, even 


The Treasure Hunters 

more hot-tempered than Filippo. A year or two earlier, at the age of 
fifteen, he had landed himself in trouble with magistrates in Pistoia for 
striking a German over the head with a large stick, and many years later he 
would travel to Ferrara intent upon murdering one of his runaway 
apprentices. His patrons likewise felt his wrath: if one of them refused to 
pay the full price for a statue, Donatello would demolish it in a fit o{ 

The two young men lived like vagabonds, paymg little attention to what 
they ate, how they dressed, or where they slept. Together they began 
digging among the vast ruins, hiring porters to cart away the rubble and 
becoming known to locals as the 'treasure hunters' because it was believed 
they were searching for gold coins and other treasures — an impression 
reinforced whenever they excavated earthenware pots filled with antique 
medals. Their activities may have attracted suspicion and even fear, not 
merely because they were suspected of practising geomancy (the art of 
divining the future by interpreting the patterns made by handfuls of 
scattered earth), but because pagan fragments were considered bad luck. In 
the fourteenth century, for example, the Sienese had unearthed an ancient 
Roman statue and, after placing it on the fountain in their main piazza, 
suffered a military defeat at the hands of the Florentines. The statue was 
promptly removed from the piazza and, in order to curse their enemies, 
reburied in Florentine territory. 

What exactly Filippo sought in these excavations was unknown even to 
Donatello. Antonio Manetti claims that Filippo, secretive as ever, made his 
study of the ancient ruins while pretending to be doing something else. He 
inscribed on strips of parchment a series of cryptic symbols and Arabic 
numbers: a secret code, that is, like the reversed handwriting that Leonardo 
da Vinci would later use to describe his own inventions. Before patents or 
copyrights, scientists frequently resorted to ciphers in order to conceal 
their discoveries from jealous rivals. Two centuries earlier the Oxford 
philosopher Roger Bacon, known as 'Doctor Mirabilis' for his experiments 
with telescopes, flying machines and robots, claimed that no scientist 


Brunelleschi's Dome 

should ever write of his discoveries m plain language but must resort 
instead to 'concealed writing'.''' 

What was the purpose of Filippo's cryptic symbols and Arabic 
numerals, the latter of which the Commune of Florence had banned m 
1296? Manetti claims he was surveymg the antiquities of Rome, measuring 
their heights and proportions. He fails to record what method Filippo 
used, but he could have determined the height of columns or buildings 
with an upright rod. This method would have been familiar to him from 
Leonardo Fibonacci's Practica geometriae, a work that was studied in the 
schools of Florence. Or he could have employed a quadrant or, even more 
simply, a mirror, whose use for mensuration Fibonacci likewise describes. 
The surveyor placed the mirror on the ground some distance in front of 
the object to be measured, then moved himself into a position such that 
the top of the object appeared in the centre of the mirror. The height of 
the building was then calculated by multiplying the distance between the 
object and the mirror by the height of the observer divided by his own 
distance from the glass. 

Filippo was not the first person to survey the ruins of Rome. As early as 
1375 Giovanni de' Dondi, the famous clockmaker, measured the obelisk of 
St Peter's, a process which he described in his book Roman Journey. But the 
knowledge that Filippo sought to uncover was unique. In calculating the 
proportions of columns and pediments he determined the measurements 
specific to the three architectural orders (Doric, Ionic and Corinthian) that 
had been invented by the Greeks and then imitated and refined by the 

*■ The histon' of science is full of such codes. The English scientist and inventor Robert 
Hooke would keep secret his discovery of the law of elasticity by means of an anagram — 
CEIIINOSSSTUU - which, once unscrambled, read UT TENSIO SIC VIS ('As the elongation, 
so the force'). There were, naturally, pitfalls to this method of encryptment. Galileo used a 
cipher to announce to Johann Kepler his discovery of the rings of Saturn, an anagram which, 
once unscrambled, should have read: OBSERVO ALTISSIMUM PLANETAM TERGEMINIM 
('I have observed the most distant of planets to have a triple form'). Kepler, however, 
companionship, children of Mars'), thereby leading to the longstanding erroneous notion that 
Saturn was possessed of two moons. 


The Treasure Hunters 

Romans. These orders were governed by precise mathematical ratios, a 
series o{ proportional rules that regulated aesthetic effect. The height of a 
Corinthian entablature, for example, is a quarter of the height of the 
columns on which it stands, while the height of each column is ten times 
its diameter, and so forth. Numerous examples of these three orders 
existed in Rome m the early 1400s. The columns in the Baths of Diocletian 
are Doric, for instance, while those at the Temple of Fortuna Virilis 
feature the Ionic, and the portico of the Pantheon the Corinthian. The 
Colosseum makes use of all three: Doric on the lowest level, Ionic on the 
second, and Corinthian at the top.^ 

Knowing that a dome was planned for the cathedral in Florence — a 
dome that no one as yet knew how to build — Filippo must have taken a 
special interest in the methods of vaulting used by the ancient Romans. In 
the early years of the fifteenth century any number of domes would have 
been available for him to scrutinise. After large parts of the city were 
burned in the fire of AD 64, Nero had established regulations (much like 
those adopted after the Great Fire of London in 1666) that widened the 
streets, controlled the water supply and — most vital from an architectural 
perspective — restricted the use of inflammable building materials. The 
Romans therefore started to use concrete, a new invention, in their 
buildings. The secret of Roman concrete was in its mortar which 
contained a volcanic ash made available by active volcanoes such as 
Vesuvius. Combined with lime mortar, it resulted in a strong, fast-setting 
cement to which an aggregate of small broken stones was added. Unlike 
conventional mortars made from quicklime, sand and water, which set 
only when the water evaporates, 'pozzolana concrete' (as it is known) 
combines chemically with water so that, like modem Portland cement, it 
cures swiftly, even under water. Although various Roman baths had been 
vaulted in concrete since the first century BC, extensive and inventive use 
of concrete arches and domes was made only after the fire of AD 64. The 
history of domes commences, effectively, with the opportunities created by 
this great conflagration — one that the Romans believed was either the 
work of Nero himself or else that of the wrathful gods. 


Brunelleschi's Dome 

The Domus Aurea, or the Golden House of Nero, begun immediately 
after the fire bv the architects Severus and Celer, shows the confident use 
of concrete to exploit new architectural shapes. This splendid urban palace 
stretched from the Palatine to the Esquiline across an area that had been 
decimated by the fire. Enormously expensive to build, it contained 
elaborate decorations, including the Laocoon (which would be rediscovered 
there in 1506), and mechanical wonders such as pipes concealed in the 
ceiling of the dining hall that sprayed perfumes on the Emperor's dinner 
guests. Its most interesting architectural feature, however, is an octagonal 
room in the east wing that is roofed by a dome whose span is some 35 feet 
across. The octagonal shape must have interested Filippo, who would have 
known, of course, that the dome of Santa Maria del Fiore, though much 
larger, was also intended to be eight-sided. 

Of even more interest to Filippo would have been the Pantheon, the 
Emperor Hadrian's temple to the gods of all the planets, executed between 
AD 118 and 128. Unlike the octagonal cupola in the Domus Aurea, the 
dome of the Pantheon is colossal, spanning 142 feet internally and rising to 
a height of 143 feet. Almost thirteen centuries after its construction it was 
still the largest dome ever built and it had escaped plunder because it was 
now converted into a church, Santa Maria Rotonda. The modern Romans 
and pilgrims alike were amazed by the immense dome. With no visible 
signs of support, it seemed to defy the laws of nature. They called it the 
'house of devils', attributing its construction not to the skilled engineers of 
the ancient world but rather to the sinister forces of demons. 

What structural features of this 'house of devils' might Filippo have 
studied? The architects of the Pantheon faced the statical problems 
encountered by builders of all domes: how to counteract the forces that act 
on any vault. These forces are separated into 'push' and 'pull' energies, 
known respectively as compression and tension. All elements in a building 
— its columns, arches, walls, roof beams — are subject to one or other 
of these actions: their stone or timber beams are compressed from 
above (which causes them to shorten) or pulled from the side (which 
causes them to stretch). An architect must design a structure 


4- The Pantheon. 

Brunelleschi's Dome 

that will counteract these pressures by playing them off against each other 
— a game of action and reaction — and channellmg them safely to the 

The first tv'pe of pressure does not create msurmountable problems for 
an architect. Stone, brick and concrete all possess such enormous 
compressive strengths that buildings can be raised to colossal heights 
without the blocks of stone crushing at the base. The tallest spire in 
England, that of Salisbury' Cathedral, stands 404 feet high, and the two 
towers of the cathedral in Cologne each rise to 511 feet, or the equivalent of 
a fifty-storey building. At this height they are almost a dozen feet taller 
than the Great Pyramid at Giza, another edifice whose tremendous size 
is made possible by the strength of the stone blocks from which it was 
built. Yet not even these soaring structures come close to exhausting the 
compressive strength of stone: a column of limestone could be built to a 
height of 12,000 feet, or over two miles high, before starting to crush under 
its own weight. 

The stones in a dome, however, are not only crushed from above but 
also thrust outward by the pull energy known as 'hoop stress', in the same 
way as the rubber of an inflated balloon will bulge outwards if one 
compresses it from above. The problem for architects is that stone and 
brick do not respond nearly so well to this lateral thrust as to compression. 

The Romans seem to have possessed some understanding of the 
structural problems created by tension and compression and they 
attempted to solve them by making extensive use of the new pozzolana 
concrete. Where the horizontal stress is greatest, at the base of the dome, 
the concrete wall of the Pantheon was built to a massive thickness of 1:^ 
feet. It then tapers to only two feet at the top, at which point a round 
window or 'oculus' is left open. Five thousand tons of concrete were 
poured in horizontal layers on to wooden formwork, but at the top of the 
dome lightweight aggregates such as pumice and, more inventive still, 
empty amphorae (clay bottles used for shipping olive oil) were added to the 
concrete in place of stone in order to reduce the load. The inside of the 


The Treasure Hunters 

Dome after 


Dome before 


Outward Motion 

5. Hoop stress. The dotted Kne shows how the dome is deformed 

by weight at the top. 

dome was also coffered, which not only lightened the load stiU further but 
also added a decorative feature that has since been extensively imitated. 
The Pantheon would have presented Filippo with proof that it was 
possible to span a space as vast as that at Santa Maria del Fiore. Yet 
Hadrian's architects were not entirelv successful, for a series o£ cracks are 
visible along the inside o{ the dome, running like lightning strokes down 
the ceiling to the springing line, the point where the dome begins to curve 
inwards. These fractures are the result of the hoop stress that causes the 
dome to spread at its haunches, stretching the fabric horizontally around 
the circumference. Filippo could have seen a similar pattern of radial 
cracks around the base of the semidome in the Baths of Trajan, and indeed 
such cracks have been an all too common feature of masonry domes. 
Containment of this horizontal stress — one that it appears not even a 
concrete wall 23 feet thick could neutralise — was therefore o{ paramount 
importance m constructing a stable cupola. For all their ingenuity, not 
even the Romans, it seemed, could provide the solution to the challenge 
laid down by Neri di Fioravanti and his committee. 

It is not known exactly how long Filippo staved in Rome or when 
precisely he left. He appears to have lived there, off and on, for more than 

Brunclleschi's Dome 

ten years, with occasional returns to Florence. His stav in Rome was one 
of the first examples o{ a new kmd of quest. Pilgrims of a different varietv^ 
soon began arriving in the cit\% ones seeking relics other than the bones of 
saints on display in the Christian churches. The image o{ Rome would be 
transformed during the Renaissance. Far from being condemned for its 
pagan associations, the ancient cit\' came to be venerated for its 
architecture, its statuar\' and its learning. The architects Leon Battista 
Alberti, Antonio Filarete, Francesco di Giorgio and Michelangelo were all 
to follow in Filippo's footsteps, travelling to Rome to take their 
inspiration from the ruins. No longer was it considered bad luck to 
unearth pagan remains, either in Rome (where Cicero's house was 
excavated) or elsewhere. In 1413, for example, the bones of the Roman 
historian Livv were exhumed in Padua, causing an outburst o{ almost 
religious fervour. The bones were enshrined in Padua's Town Hall, and 
soon afterwards the city fathers received from Alfonso, King of Naples, 
the urgent request for a femur. An even more spectacular relic was the 
perfectly preserved body of a young Roman girl excavated from one of the 
tombs along the Via Appia and exhibited to the populace of Rome in 

Other treasures were also discovered. Manuscripts were disinterred from 
where they had lain entombed throughout the centuries. The Annals of 
Tacitus, Cicero's Orator and De oratore, the poems of TibuUus, Propertius 
and Catullus (the lone manuscript of whose work was found stoppering a 
wine barrel), the Satyricon of Petronius, the poems of Lucretius, a complete 
copy of Quintilian's Institutio oratoria — all of these shards of ancient Rome, 
lost or unknown for centuries, were recovered in the first decades of the 
fifteenth centur\'. Like the fragments of stone studied by Filippo, such 
manuscripts would form a link between the ancient Romans and the 
artists, philosophers and architects of the Quattrocento. And it was from 
these broken stones and faded parchments that the world would now be 
made afresh. 


An Ass and a Babbler 

WHEN HE RETURNED permanently to Florence, probably in 
1416 or 1417, Filippo moved back into his childhood home 
near the cathedral, a good vantage point for a man obsessed 
with the architectural puzzle presented by the dome to survey its progress. 
He would have found that much had been accomplished on the cathedral. 
The tambour, or drum, had been constructed between 1410 and 141 3, with 
walls fourteen feet thick in order to support the weight of the cupola. In 
141 3 a large new crane had been built to raise materials, and two of the 
three tribunes of the octagon had been vaulted. The church had also just 
acquired its new name, Santa Maria del Fiore, 'Our Lady of the Flowers', 
having previously been referred to as Santa Reparata, the name o{ the older 
cathedral which was now completely demolished. 

Now in middle age, Filippo was short, bald and pugnacious-looking, 
with an aquiline nose, thin lips and a weak chin. His appearance was not 
helped by his dirty and dishevelled clothing. Yet in Florence such an 
unsightly display was almost a badge of genius, and Filippo was simply the 
latest in a long and illustrious line of ugly or unkempt artists. The name of 
the painter Cimabue means 'ox-head', and Giotto was so unattractive that 
Giovanni Boccaccio devoted a tale to his appearance in the Decameron, 
marvelling at how 'Nature has frequently planted astonishing genius in 


Brunelleschi's Dome 

men of monstrously ugly appearance'. Later, Michelangelo would become 
legendar\' for his ugliness, which was partly the result of a broken nose 
earned m a fracas with the sculptor Pietro Torrigiani. And like both 
Giotto and Filippo, Michelangelo was indifferent to the state of his dress, 
often going for months on end without changing his dogskin breeches. In 
the end, ugly and eccentric artists would become so much the norm that 
Filippo's biographer, the painter and architect Giorgio Vasari — himself an 
uncouth man, with a skin disease and dirty, uncut fingernails — marvelled 
that an artist as talented as Raphael should actually have been physically 

Perhaps unsurprisingly, Filippo was unmarried. But although in 
Florence bachelorhood was not unusual for a man in his forties, since men 
married late and generally took much younger women as their brides, 
Filippo would never marry, and in this abstention from family life he also 
became part o{ a long and glorious tradition of artists that included 
Donatello, Masaccio, Leonardo da Vinci and Michelangelo. Many 
Florentine artists and thinkers took a dim view of both marriage and 
women. Boccaccio, who never married, had criticised Dante for having 
done so, claiming that a wife was a hindrance to study. 

No sooner was he settled in Florence than Filippo took steps to become 
involved in the cupola project. In May 1417 the Opera del Duomo paid 
him 10 florins for drawing plans of the dome on parchment. What these 
plans showed is not recorded, but Manetti reports that Filippo's advice 
had been eagerly sought by the wardens after his return from Rome. That 
he should have insinuated his way into the heart of such an important 
project at this stage is possibly surprising, regardless of his growing 
reputation as a student of Roman vaulting techniques. Despite his 
youthful promise as a metalworker he had, at the age of forty-one, 
accomplished relatively little in practical terms. In 1412 he had given advice 
on the construction of the cathedral in the nearby town of Prato, but the 
work being done there was decorative rather than structural, entailing the 
encrustation of the church's fagade with the dark-green stone known as 
serpentine. And so far he had failed to receive a single architectural 


An Ass and a Babbler 

commission except for a house near the Mercato Vecchio that he had built 
for his kinsman Apollonio Lapi. 

By 1418 Filippo was probably best known for an experiment m Imear 
perspective ^ This experiment must have been conducted in or before 1413, 
when Domenico da Prato refers to him as 'the perspective expert, 
ingenious man, Filippo di Ser Brunellesco, remarkable for skill and fame'. 
It was one of the first o£ Filippo's many innovations and a landmark in the 
history of painting. 

Perspective is the method of representing three-dimensional objects in 
recession on a two-dimensional surface in order to give the same 
impression of relative position, size or distance as the actual objects do 
when viewed from a particular point. Filippo is generally regarded as its 
inventor, the one who discovered (or rediscovered) its mathematical laws. 
For example, he worked out the principle of the vanishing point, which 
was known to the Greeks and Romans but, like so much other knowledge, 
had long since been lost. Greek vase paintings and marble reliefs show an 
understanding of perspective, as do some of the scene paintings for Greek 
tragedies staged in Athens, including those of Aeschylus. The Roman 
scientist Pliny the Elder claimed that this method of representation (which 
he calls imagines ohliquae, or 'slanting images') had been invented by a painter 
of the sixth century BC named Kimon of Kleonai. The Romans made use 
of perspective in their wall paintings, and some of its principles were 
described by the architect Vitruvius. Furthermore, it seems inconceivable 
that buildings such as the Pantheon or the Colosseum could have been 
built without their architects executing perspective drawings of some sort. 

After the decline of the Roman Empire, however, the technique of 
perspective drawing was lost or abandoned. Plato had condemned 
perspective as a deceit, and the Neoplatonist philosopher Plotinus (AD 
205—270) praised the flattened art of the ancient Egyptians for showing 
figures in their 'true' proportions. This prejudice against the 'dishonesty' of 
perspective was adopted in Christian art, with the result that naturalistic 
space was renounced throughout the Middle Ages. Only in the first 
decades of the fourteenth century did the ancient methods of perspective 


Brunelleschi's Dome 

reappear when Giotto began using chiaroscuro — a treatment of light and 
shade — to create realistic three-dimensional effects. 

Filippo might have seen examples of ancient perspective painting during 
his travels through Italy. But he probably worked out the principles o{ 
perspective from quite different sources. The procedures for executing his 
own painting — plotting lines of sight on a plane surface — he could have 
learned from the surveying techniques he employed while measuring the 
ruins o{ Rome. Persperrive dray^^ina i«; ^ fter all, similar to surv eying in 
that both involve determining the relative positions of three-dimensional 
objects for the purpose of protracting them on paper or canvas. The 
practice of measuring and surveying was highly developed by Filippo's 
time: his great leap appears to have been an application of its principles 
and techniques to the art of painting. 

Filippo's experiment consisted of an almost magical optical trick, a 
trompe Voeil painting that, in its clever confusion of life and art, prefigured 
much later experiments with optical devices such as camera obscuras, 
panoramas, dioramas and catoptric art. This painting — one of the most 
famous in the histor^^ of art — has long since been lost to the world. Last 
known to have been in the possession of Lorenzo the Magnificent, it 
vanished after the occupation of Florence by Charles VIII of France in 
1494, when many works of Florentine art were looted. It was clearly 
described, however, by Antonio Manetti, who claimed to have held it in 
his hands and attempted the experiment himself. 

For the subject of his perspective painting Filippo chose one of 
Florence's most familiar sights: the Baptistery of San Giovanni. Positioning 
himself a short distance inside the middle portal of Santa Maria del Fiore, 
some 115 feet from the Baptistery, he painted on to a small panel, in perfect 
perspective, using a geometrically constructed picture plane, everything 
that was visible through the Trame' of the cathedral's doorway: the 
Baptistery and its surrounding streets, including the wafer-makers in the 
Casa della Misericordia and the corner of the sheep market. In place of a 
painted sky he substituted a piece of burnished silver, a mirror that would 
reflect the clouds, birds and changing sunlight of the actual sky. Finally, he 
drilled a small hole the size of a lentil bean into the vanishing point of the 


An Ass and a Babbler 

painting, or that central point on the horizon where the receding parallel 
lines appear to converge. 

The panel was then 
ready for demonstration. 
Standing six feet inside 
the doorway of Santa 
Maria del Fiore — on the 
exact spot, in other 
words, where Filippo had 
executed the panel — the 
observer was to turn the 
painted side of the panel 
away from himself and 
peer through the small 
aperture. In his other 
hand he was to hold a 
mirror, the reflection of 
which, when the glass was 
held at arm's length, 
showed (in reverse) the painted image of the Baptistery and the Piazza San 
Giovanni. So lifelike was this reflection that the observer was unable to tell 
whether the peephole revealed the actual scene that should have been 
before him — the 'real scene' lying beyond the panel — or only a perfect 
illusion of that reality. 

6. Diagram of the optical instrument used by 
Brunelleschi to render the Baptistery in 
perspective. The painting is on the left, the 
mirror on the right. 

When the competition for the model of the dome was announced in 
August 1418, Filippo must have jumped at the chance. In June the aged and 
infirm capomaestro Giovanni d'Ambrogio, who had been called back into 
service from retirement in 1415 following the premature death of his 
successor, Antonio di Banco, had built a model for the cupola's 
scaffolding. But this model cannot have been especially inspiring as the 
Opera saw fit to invite other attempts only two months later. With the 
prize of 200 florins at stake, Filippo and eleven other competitors 


Brunelleschi's Dome 

hopefully submitted their models. The 1367 model was still sacrosanct, of 
course: the problem at hand was its practical execution. 

How to build the invisible supports demanded by the model — the 
circumferential chains that had been the subject of such debate in 1366—7 — 
was still a vexed question. Also essential to the project was the resolution 
of a difficulty not fully considered by Neri and his group: the temporary 
wooden framework, or 'centring', needed to support the masonrv of the 
dome while the mortar cured. Except in the Near East, where there was a 
shortage of strong timber, all masonr\' vaults were (and still are) 
constructed on wooden frameworks that are supported either by 
scaffolding or from the ground. In the cases of most small-span arches the 
process is relatively simple. A timber centre is built to the desired profile in 
order to support the stones comprising the arch. This structure has to be 
both strong enough to bear the weight of the masonr)' and rigid enough to 
resist bending under the incremental loading of the blocks of stone. It also 
has to be easy to remove when the time comes. 

It is sometimes possible to build 
perfectly spherical domes without this 
sort of centring because each circular 
layer of masonry forms a self-sustain- 
ing horizontal arch. As one of Filip- 
po's friends, Leon Battista Alberti, 
explained in his treatise on architec- 
ture: 'The spherical vault, unique 
among vaults, does not require cen- 
tring because it is composed not only 
of arches but of superimposed rings.' 
Each stone or brick, that is, forms part 
of a horizontal as well as a vertical 
arch and is therefore held in place by the pressures of the surrounding 
masonry'. But the shape of the cupola in Florence, dictated by the 1367 
model, was not circular but octagonal and pointed, meaning that the 

7. Wooden centring supporting 
an arch. 


An Ass and a Babbler 

horizontal courses of masonry would not be continuous, as in a circular 
dome, but broken at each of the eight corners. 

The construction of a w ooden cen tring for the dome of Santa Maria 
del Fiore therefore appeared essential. Yet its design presented the wardens 
with major difficulties, both technical and financial, first and foremost 
because the centring, like the dome itself, would have to be a structure 
unprecedented in scale. Innumerable trees had to be found for the required 
timber. As the competition was being proclaimed, thirty-two large tree 
trunks were delivered to the Opera and cut into 900 feet of planks and 135 
stripped beams for use in the scaffolding, centring and loading platform of 
the south tribune of the cathedral, now ready for vaulting. The cupola, 
however, was to be much larger than the tribune and would therefore have 
required, m one estimate, twenty times as much wood, or as many as 700 
trees. The Opera owned a number of forests on the slopes of the 
Apennines, but timber was rivalled only by marble for its expense and the 
logistical difficulties of its acquisition, being in short supply and, in the 
absence of hydraulic saws, extremely labour intensive. It was perhaps an 
omen that the capomaestro Antonio di Banco died while on a trip in search 
of timber supplies with which to build the centring for the dome. 

Even if sufficient numbers of good quality trees could be found, and 
even if the expense of sawing the wood and assembling the vast structure 
could be absorbed, other problems would have confronted the wardens. 
The act of decentring — the removal of the wood from beneath the 
finished vault — was one of the most hazardous operations in the entire 
building process. During the Middle Ages the most usual method of 
decentring was to set the supporting poles of the centre's scaffolding in 
sand-filled kegs and then, at the time of striking, to unplug the kegs and 
allow the sand to escape, thereby slowly lowering the level of the wooden 
framework. This operation may seem simple, but timing was a major 
problem. Medieval mortars remained 'green' for up to a year or even 
eighteen months, until the water necessary for crystallisation had 
completely evaporated. The centring for the vaults of the south tribune, 
for example, remained in place for thirteen months, from June 1420 until 


Brunelleschi's Dome 

July 1421, thus tying up a large amount of timber that could have been 
reused elsewhere — for example, m the loading platform for the cupola. If 
centring was struck too early, the mortar would still be plastic and its 
strength insufficient. On the other hand, long-term loadings create a 
deformation of wood known to engineers as 'creep': if the centring was left 
in place for too long the timber would warp beneath the weight of the 
vault it supported, causing the masonry to shift. This phenomenon was 
known to the ancient Greeks, who would remove the wheels of their 
chariots at night, or else prop the chariots vertically against a wall (as 
Telemachus does in Book IV of the Odyssey^ in order to prevent the wheels 
from warping under the weight of the stationary vehicles. 

A final difficulty was that the centring for such a massive dome would 
have been awkward and obtrusive, even when erected in an area as large as 
the cathedral's central octagon. Vast in scale, running from the ground to 
the oculus — the open window at the top of the dome — it would have 
crowded the octagon and left little room for the masons to manoeuvre. 

One design for the dome's centring existed already, a legacy of Giovanni 
di Lapo Ghini, the capomaestro whose plan for the cupola had lost out to 
Neri di Fioravanti's. His wooden model of the centring, executed in 1371, 
sat inside Neri's 1367 model. But evidently this model, like that of 
Giovanni d'Ambrogio, was inadequate to the task. 

By the end of August, barely two weeks into the competition, Filippo 
had already begun building a brick model of the cupola. The wardens of 
the Opera appointed four master masons to assist with its construction. 
They must have been taken aback by what they saw, perhaps suspecting 
Filippo of preparing a clever illusion like his painting of the Baptistery, 
one that would deceive the senses and defy the laws of reason. As with his 
panel, Filippo set about his task with meticulous craftsmanship. For the 
woodwork he had hired two of Florence's most gifted sculptors, his friend 
Donatello and also Nanni di Banco, the son of the late capomaestro and a 
man who had worked on the cathedral for over ten years. The four masons 
sent from the Opera spent a total of ninety days working on the model. 

Constructed in one of the courtyards of the Opera, Filippo's model was 


An Ass and a Babbler 

the size of a small building, requiring forr\'-nine cartloads of quicklime 
and over 5,000 bricks. It had a span ot over six feet and stood twelve feet 
tall, easily high enough for the wardens and various consultants to walk 
inside to inspect it. And like man\' architectural models it must also have 
been an exquisitely rendered work of art, for the carvings bv Donatello and 
Nanni di Banco — two men whose brilliantly lifelike sculptures adorned 
the tacade and side portals of the cathedral — had been gilded and painted 
bv the artist Stefano del Nero. 

Although the competition was originally intended to end on 30 
September, it was extended by two more months, perhaps to allow Filippo 
to complete his elaborate model, or to give some o{ his rivals, masters 
from Pisa and Siena, time to transport themselves and their models to 
Florence. Not until December 1418 did a Great Council consisting of the 
thirteen wardens along with consuls of the Wool Guild and various 
consultants assemble in the nave of the cathedral to consider the various 
designs. After bread and wine were ser\'ed, the models were discussed. 
Filippo's brick model m particular received a good deal of attention, both 
on 7 December and then a fortnight later, when its merits were debated 
over a period of four days. 

The documents of the Opera del Duomo record these bare facts and 
nothing more. But Filippo's two biographers, Manetti and \'asari, relate a 
livelier tale. Despite assurances in the original proclamation of August 1418 
that all models would find a bene et gratiose audietur — a 'friendly and 
trustworthy audience' — Filippo's proposal was greeted by the wardens and 
Its chosen experts with scepticism and even, at times, outright hostilit)'. 

The reasons for these reactions are not difficult to understand. Filippo 
had approached the problem of the centring m a revolutionan' manner, 
one utterly different from his rivals'. Everyone else took it for granted that 
an elaborate framework would be required to support the masonn' of the 
rising dome; the only questions were ones of economics and design. One 
of the proposals put forward involved sustaining the cupola on a 
temporarA^ mound of earth piled to a height of 300 feet. This project is not 
actually as ridiculous as it might sound since Romanesque vaults were 


Brunelleschi's Dome 

sometimes built over rooms that had been filled with earth. Indeed, as late 
as 1496, soil heaped to a height of 98 feet was used as a centring for the 
vaults m the cathedral at Troyes. But the proposal was met with derision 
in the Great Council. One of the wardens suggested, with withering 
sarcasm, that coins should be mixed into the dirt so that when the time 
came to decentre the immense vault the citizens of Florence would be 
eager to lend a helping hand. 

Filippo, on the other hand, offered a simpler and more daring solution: 
he proposed to do away with the centring altogether. This was an 
astounding proposal. Even the smallest arches were built over wooden 
centring. How then would it be possible to span the enormous diameter 
called for in the 1367 model without any support, particularly when the 
bricks at the top of the vault would be inclined at 60-degree angles to the 
horizontal? So astonishing was the plan that many of Filippo's 
contemporaries considered him a lunatic. And it has likewise confounded 
more recent commentators who are reluctant to believe that such a feat 
could actually have been possible.^ 

Filippo did himself few favours when he appeared before the Great 
Council to expound his revolutionary design. Anxious, as usual, that no 
one should steal the fruits of his lngenuit\^ he stubbornly refused to 
divulge to the wardens the explicit technical details of his plans. The 
wardens, naturally, were little impressed by this sort of coyness. They 
pressed Filippo to elaborate. He refused. So heated did the exchanges 
become, according to Vasari, that he was first derided as 'an ass and a 
babbler, then physically ejected from one of the more unpleasant 
assemblies. Many years later he would confide to Antonio Manetti that he 
had been ashamed to show his tace in the street for fear of being taunted 
as 'that madman who utters such nonsense'. His ingenious plan looked 
like a lost cause. 

Filippo was naturally incensed by this treatment, and the experience 
served to confirm his low opinion of what, ten years later, he would call 
'the ignorant crowd'. But in Florence, as Vasari notes, no one's opinion 
remains unchanged for long, just what won the wardens round to the 


An Ass and a Babbler 

merits of Filippo's project is unclear. Vasari relates an anecdote that is as 
amusing as it is improbable — a legend like that of Archimedes in his 
bathtub or Newton under the apple tree. In this parable Filippo suggests 
to the wardens that whoever can make an egg stand on end on a flat piece 
of marble should win the commission. When all of the other contestants 
fail the test, Filippo simply cracks the egg on the bottom and then stands 
it upright. When his rivals protest that they might have done the same, 
Filippo retorts that they would know how to vault the cupola, too, if only 
they knew his plans. And so the commission, Vasari claims, promptly 
went to Filippo. 

It seems unlikely in the extreme that the serious-minded wool magnates 
of the Opera del Duomo would be tempted to hand over the commission 
on the basis of such a parlour trick. Implausible as the story sounds, 
however, it is worth noting how the humble egg has long fascinated 
scientists and engineers. Both Alexander of Aphrodisia and Pliny the Elder 
marvelled at the longitudinal strength of this apparently flimsy structure 
that, as the latter states, 'no human force can break'. Galileo, too, would 
ponder the phenomenon. In a fragment dedicated to his son he enquires: 
'Why is it that an egg held with your hands by its top and bottom and 
pressed with great force cannot be crushed?' His pupil Vincenzo Viviani 
resumed the topic, going so far as to speculate that the egg — or, rather, a 
half eggshell, placed upside down — was the inspiration behind the 
architecture of the domed vault. 

The egg anecdote aside, the results of the deliberations by the Opera 
were not as clear-cut and decisive as Vasari implies, though in December 
1418 most of the other models were indeed eliminated from consideration. 
The panel of judges fixed their attention on the two remaining designs, 
one of which would be selected as the basis for the dome's construction. 
Histor\' had begun repeating itself. The first model was, of course, 
Filippo's. The second, also made of brick, and also built m one of the 
Opera's courtyards, had been designed by his old adversary, Lorenzo 


The Rival 

THE PREX'IOL'S SIXTEEN years had treated Filippo's fellow 
goldsmith verv' well. At the age of fortv, Lorenzo Ghiberti had 
become one of the most renowned artists in all of Italy. He was 
bald like Filippo but, unlike Filippo, looked mem' and avuncular, with a 
moon face and a large, fleshy nose. As was the custom in Florence, he had 
married late, at the age of thirtv-seven, taking as his bride a sixteen-year- 
old, Marsilia, the daughter of a wool-comber, who promptly gave him two 
sons. Most of his time was spent m his workshop opposite the convent of 
Santa Maria Novella, where, after almost two decades of work, he was still 
busy casting the doors for the Baptister)' in a giant, purpose-built furnace. 
Thus far he had melted almost 6,000 pounds of bronze for the project. 
Lorenzo was a prosperous man by now, with a house in Florence and a 
vineyard in the country. As his stepfather Bartoluccio had prophesied in 
1401, he was no longer required to make earrings for a living. Since 
winning the competition for the Baptistery doors he had been kept busy 
with commissions: tombs in marble or bronze, candelabras, shrines, reliefs 
for the baptismal font in Siena Cathedral and a bronze statue of St John 
the Baptist for the Guild of Cloth Merchants. Completed in 1414 and 
installed in a niche at Orsanmichele, this statue, at almost nine feet tall, 


The Rivals 

was the largest work in bronze ever cast in Florence — a testament to 
Lorenzo's ambition and skill. 

But Lorenzo, for all of this work, had precious little experience as an 
architect. Indeed, his model for the cupola marks his first foray into that 
field. In contrast to Filippo's, his model was neither large nor intricate. His 
four masons worked only four days each on it compared with the ninety 
spent on Filippo's. It was made from mattoni picholini, or small bricks, and 
presumably involved some sort of centring, for Lorenzo also employed a 
carpenter m its construction. This was probably the fundamental 
difference between the two models which the wardens found themselves 
obliged to choose between. 

The Rurry of activity in the last months of 1418 was followed by a lull 
of more than a year. No firm decisions were made. Christmas arrived: the 
wardens ordered geese for themselves. On New Year's Day, as usual, they 
swore their oath to build the dome according to Neri di Fioravanti's 
model. Then for a number of months they dithered and delayed. The 
cupola project languished. No one — neither Filippo nor Lorenzo — was 
awarded the prize of 200 florins. 

One of the reasons for the delay was that a crack was discovered in the 
vaulting of the north tribune. This vault had been raised little more than 
ten years earlier, so its fracture was hardly an auspicious sign under which 
to begin raising an enormous and structurally uncertain cupola. Another 
reason was that old Giovanni d'Ambrogio had been removed from his post 
as capotnaestro, having become too decrepit to ascend to the top of the vault 
to inspect the work of the stonemasons. A third reason was that, one 
month after the Great Council, events temporarily overcame the cupola 
project: in January 1419 Pope Martin V and his entourage arrived in 

Martin V had been elected pope several years earlier at the Council of 
Constance, which ended the Great Schism, the 39-year period in which the 
Roman Catholic Church was divided between rival popes in Rome and 
Avignon. The Council had deposed John XXIII, a one-time pirate and 
dedicated libertine who was said to have seduced hundreds of women, and 


Brunelleschi's Dome 

replaced him with Martin. The new pope would remain in Florence for 
the next twenty months, until Rome could be properly fortified and some 
of Its churches restored. In the meantime Florence had to be made 
hospitable for His Holiness. The Opera del Duomo therefore diverted 
masons and carpenters from the cathedral to Santa Maria Novella, where a 
sumptuous set of apartments was hastily contrived, complete with a 
staircase that the Opera commissioned from Lorenzo after a competition 
involving two other designs. This verdict must have augured well, in 
Lorenzo's mind, for the Opera's other, much larger commission. 

Filippo bided his time fruitfully during these months. He refined his 
model, adding both a lantern and a circular gallen^ around the drum. But 
by now he, like Lorenzo, was involved with other projects. The year 1419 
was, for him, an annus mirabilis of sorts. In the six months following the 
cupola competition he received four separate architectural commissions, all 
in Florence. This is remarkable in light of the fact that he had won no 
prior commissions. It suggests that, for all the ridicule to which they were 
subjected, his plans for the dome had won him a good deal of respect. 

The first of these commissions was the Ridolfi Chapel in San Jacopo 
sopr'Amo, south of the river, and the Barbadori Chapel nearby in Santa 
Felicita. Then came the sacristy m San Lorenzo, commissioned by the 
wealthy banker Giovanni de' Medici, who hoped to be entombed inside 
Filippo's creation. Finally there was the Ospedale degli Innocenti, the 
'Hospital of the Innocents', a home for abandoned infants sponsored by 
the Silk Merchants, the guild responsible for the welfare of the 
Commune's foundlings and orphans. It was also in 1419 that Filippo 
adopted, and then apprenticed, a seven-year-old orphan named Andrea 
Cavalcanti, later known as II Buggiano, after his home village in Tuscany. 
This was to be a productive if occasionally turbulent association. 

It was no coincidence that three of the four commissions awarded to 
Filippo in 1419 included cupolas. Particularly significant were the 
Barbadori Chapel and the Ridolfi Chapel. Both of these were commis- 
sioned by members of the Wool Guild, therefore by men closely involved 
with the cupola project at Santa Maria del Fiore." These two chapels 



The Rivals 

represented tests for Filippo, serving as trial runs for the novel scheme of 
vaulting without centring. Unfortunately, nothing now remains of either 
dome. The interior of San Jacopo was rebuilt in 1709, and m 1589 the 
dome of the Barbadori Chapel was demolished by Vasari (ironically, 
Filippo's ardent champion) when the long corridor was built to link the 
Pitti Palace to the Uffizi. It is therefore impossible to know whether the 
techniques Filippo used were those he later employed on the cupola of 
Santa Maria del Fiore. What we do know is that both domes were raised 
without wooden centring, although ironically the one for the Ridolfi 
Chapel was actually smaller than Filippo's brick model. 

Towards the end of 1419 the Wool consuls made a concerted effort to 
resolve the problem of the dome by appointing four men to a special ad hoc 
committee known as the Uffitiales Cupule. These Tour Officials of the 
Cupola' moved swiftly. On 16 April 1420 they assembled the thirteen 
wardens and twenty-four Wool consuls in the headquarters of the guild, 
the Palazzo dell' Arte della Lana, several streets south of the cathedral, in 
order to appoint a new capomaestro to replace Giovanni d'Ambrogio. Their 
choice was a thirty-eight-year-old master mason named Battista d' Antonio 
who had served as vice^capomaestro under Giovanni. Battista had worked on 
the cathedral site since 1398, first as an apprentice stonemason, then as a 
master. Eight other master masons were then appointed to serve under 
Battista, each being placed in charge of one of the eight sides of the 
octagonal dome. 

So omnipresent would Battista d' Antonio become at Santa Maria del 
Fiore over the next thirty years, and so neglected has his role been, that he 
has been called the 'hunchback of the Duomo'.^ Despite his title as 
capomaestro, however, he was actually more a foreman or overseer than an 
architect or designer in the mould of previous capomaestri such as Giotto or 
Andrea Pisano. These two men were first and foremost artists, the one 
having trained as a painter, the other as a goldsmith. Battista, on the other 
hand, was a mason and, like most masons, worked in traditional ways and 
according to long-established rules and precedents, imitating previous 
designs rather than inventing new ones. He would become the on-site 


Brunelleschi's Dome 

supervisor whose task it was to translate any models and plans settled 
upon by the Opera del Duomo into bricks-and-mortar reality by co- 
ordinating the efforts of the eight master masons and their crews, as well 
as the unskilled labourers on the ground. All building projects o{ the 
Middle Ages featured just such an individual, who was essential to their 
success. It was his task to describe the architect's plans to workmen unable 
to comprehend the complex architectural drawings.''' 

Since Battista d' Antonio, for all his practical experience, had no formal 
training or theoretical preparation in building design, it was necessary to 
appoint someone else who would serve, in effect, as the architect-in-chief 
rather than merely the leader of the works staff. So it was that on the same 
day that Battista was appointed, the Four Officials, the wardens and the 
Wool consuls took the extraordinary step of appointing two more 
capomaestri. Filippo's delight in finally being allowed to oversee the project 
he had been dreaming of for so long must have been tempered by the fact 
that Lorenzo Ghiberti was appointed as his fellow capomaestro. Henceforth 
the two rivals would be forced to work in close collaboration with each 
other on the project, sharing a rather meagre salary of 6 florins per month. 

This plan surely tempted fate, given Filippo's response to the result of 
the Baptistery door competition two decades earlier. But Filippo had 
invested too much time and ingenuity in the project to decline the offer in 
a fit of pique. This time he accepted his position and then carefully bided 
his time, aware that he alone, and not Lorenzo, a man with no 
architectural experience, knew how the dome would be built. 

A fourth architect was also appointed, a sixty-year-old humanist 
philosopher named Giovanni da Prato, who was made deputy to Lorenzo 
Ghiberti. Giovanni was, among various other accomplishments, the 
lecturer on Dante at the University of Florence. No sooner did he become 

* It was from these sorts of communications that, centuries later, the freemasons — a secret 
society having nothing to do with architecture — would develop their rituals. Many of their 
secret signs of recognition, for example, arc borrowed from the system of words, signs and 
touches that Hiram of Tyre, the master mason of Solomon's Temple in lenisalem, was said 
to have used m order to communicate with the vast amiy of workers under his command. 


The Rivals 

involved in the project than he began nourishing a lusty hatred for Filippo. 
The root of this hatred was a vision of the dome that differed quite 
drastically from Filippo's. In 1420 Giovanni da Prato was already agitating 
for a change in the cupola's design because he believed that it would result 
in a church that was oscvtra e tenehrosa ('murky and gloomy') due to the lack 
of windows. But his proposed plan that twenty-four windows be 
incorporated into the base of the dome (a structurally dubious scheme) 
received little attention from the Opera del Duomo: he was paid 3 florins 
for his advice, which was then completely ignored. Over the years this 
rejection would fester in Giovanni's breast and finally lead him to launch 
several remarkably vitriolic attacks on Filippo. 

Three months after these appointments were made, the wardens and the 
Four Officals of the Cupola made an even more momentous decision: they 
met to approve a written specification outlining the structural details of 
Filippo's 1418 model, which they now adopted as the one showing the best 
method of vaulting. This document is a twelve-point memorandum that 
describes the dimensions of the two shells, the systems of ribs and chains, 
the building materials to be used, and so forth. It also mentions the 
intention to vault without centring, stating that both shells are to be built 
sanza alcuna armadura ('without scaffold-supported centring'), though how 
exactly this was to be achieved the document fails to state. 

Although the author of this memorandum is not known for certain, it 
seems safe to assume it is Filippo's brainchild. Still, Filippo was not 
named as the winner of the competition: the Opera did not see fit to 
award the prize of 200 florins to him or to anyone else. This must have 
rankled Filippo given that his brick model was to become the new 
touchstone for the dome: it was put on display in the open air of the 
Piazza del Duomo, near the campanile. Like the model of Neri di 
Fioravanti, which still stood inside the cathedral, it was to become a shrine 
of sorts and would occupy this spot for the next dozen years, with a fence 
erected around it in order to foil vandals. But Filippo seems to have 
accepted the Opera's decision not to award him the 200 florins. After all, 


Brunelleschi's Dome 

he was finally to get the chance to vault the dome using his revolutionary 


Men Without Name or Family 

THE MORNING OF 7 August 1420 began with a small celebration 
held 140 feet in the air. The stone-cutters, masons and other 
labourers on the buildmg site climbed to the top of the tambour 
of Santa Maria del Fiore, high above the city, and ate a breakfast of bread, 
melons and Trebbiano wine paid for by the Opera del Duomo. This small 
feast marked a historic occasion. After more than fifty years of planning 
and delay, construction of the great dome of the cathedral was ready to 

For the previous few months the building site had been a hive of 
activity. One hundred fir trees, each 21 feet long, had been ordered for the 
scaffolds and platforms, and the first of almost a thousand cartloads of 
stone had been delivered. Peering over the edge of the tambour the 
workmen could have seen spread below them in the Piazza del Duomo 
scores of these sandstone beams, as well as hundreds of thousands of 
bricks stacked high. 

Life on the building site would not be an easy or an enviable one. The 
pay was low, the hours long, the work dangerous and the employment 
sporadic due to bad weather. Most workers in the building trade came 
fromi poor families, the popolo mimito, or little people'. The unskilled 
labourers — men who carried the lime or bricks — were known as uomini 


Brunelleschi's Dome 

senza nome e Jamiglia, 'men without name or family'. Altogether as many as 
300 men worked on the dome, including those in the quarries.' Their week 
was a long one, running from Monday to Saturday, often from dawn to 
dusk, which in the summer could mean a fourteen-hour day. Payment 
came every Saturday, when the foreman, Battista d'Antonio, issued the 
men with chits, or scrim, which were redeemed from the pay clerk of the 
Opera. If fortunate, they might be dismissed an hour or two early, giving 
them time to buy their food in the stalls o^ the nearby Mercato Vecchio, 
which, like everything else, was closed on Sundays. All work was forbidden 
on the sabbath and during religious feasts, though an exception was made 
for the men whose job it was to water the masonry on feast days in order 
to keep It moist and therefore workable. The spreading of manure over the 
walls — a common method used in the Middle Ages for keeping the 
masonry moist and protecting it from the elements — does not appear to 
have been employed at the cathedral. One reason for this might have been 
that, for reasons o^ hygiene, it was illegal to import manure into the cit\^ 

Religious feasts offered the masons what must have been a welcome 
relief from their work. On these days they would march in procession 
through streets swept clear of prostitutes and moneylenders or else make 
pilgrimages in search o^ the indulgences sold in stalls along the Via San 
Gallo. Their most important festival was the eighth o( November, the 
feast of their patron saints, the Quattro Coronati: four Christian sculptors 
martyred by the Emperor Diocletian for refusing to carve a statue o^ the 
pagan god Aesculapius. On this day the men would hear a Mass together, 
then take food and drink — the latter sometimes to excess, for the guild's 
statutes state that some o^ the men conducted themselves on this solemn 
occasion come se fussino alia taverna, 'as if they were in a tavern'. 

Taking the sabbath and these religious feasts into account, a full-time 
labourer could expect approximately 270 days of work on the dome each 
year, though in fact because of the weather he would probably work a 
good deal less, perhaps as few as 200. When it was too cold, wet or windy 
for anyone to work on the summit, the names of all the masons would be 
put into a leather pouch and Battista d'Antonio would draw those of five 


Men Without Name or Family 

men, who were set to work in the shelter, plastering or bricklaying, while 
the rest of the workers were sent home without pay. Longer layoffs were 
also a possibility. 

These were the uncertam conditions, then, in which the masons would 
set off for the cathedral each working day. Church bells rang in every 
district of the city to rouse them from their beds and summon them to 
their labours. They carried their own tools, which the Opera expected 
them to supply themselves: chisels, T-squares, hammers, trowels and 
mallets, all of which could be repaired or sharpened by a blacksmith who 
operated a forge on the site. Upon arriving at the cathedral the men had 
their names inscribed on a gesso-board, rather like punching a clock in a 
factory, while the working hours were recorded by a sand hourglass. 
Filippo appears to have been a strict master. Later he would institute an 
even more precise form of discipline on the building site of Santo Spirito, 
where an oriuolo di mezzoro, a half-hour clock, regulated the working day by 
chiming every thirty minutes. The conception of time was changing in the 
fifteenth century. Throughout the Middle Ages it had been associated with 
the liturgical hours. The Latin word hora, or 'hour', was in fact 
synonymous with prayer. Each of these hours had been divided into four 
parts ox ten minutes' duration, while each minute was divided into forty 
'moments'. By 1400, however, it had become the custom to divide the hour 
into sixty minutes, and each minute into sixty seconds. The pace of life 
was increasing." 

Besides their tools, the men also carried their food with them in leather 
pouches. The noon meal, the comesto, was taken at eleven o'clock, when the 
church bells sounded a second time. We know that the comesto was 
normally eaten aloft because in 1426, in order to foil idlers, the Opera 
decreed that no mason could descend from the dome during the day. This 
must have meant that even on the hottest summer days the workers did 
not enjoy their dolce Jar niente, or 'sweet idleness', the afternoon siesta when 
aU labours would usually cease because of the scorching temperatures. It 
was also in 1426 that, on Filippo's orders, a cookshop was installed 
between the two shells o{ the cupola in order to serve a noon meal to the 


Brunelleschi's Dome 

workers. The dangers of an open fire on the dome were possibK' mitigated 
by the fact that the masons also served as Florence's firemen. This 
responsibility fell to them because they owned the tools used to combat 
fires in the only way that was practical: tearing down walls to create fire- 

To slake their thirst on sweltering summer days the workers drank 
wine, which they carried in flasks along with their tools and lunches. 
Strange and inadvisable as a draught of wine might seem under these 
circumstances, whether diluted or not, wine was a healthier drink than 
water, which carried bacteria and therefore disease. And the Florentines 
placed great faith in the wholesome properties of wine. Drunk in 
moderation, it was said to improve the blood, hasten digestion, calm the 
intellect, enliven the spirit and expel wind. It might also have given a fillip 
of courage to men clinging to an mward-curving vault several hundred feet 
above the ground. 

The stonemasons eating their breakfast on the tambour that historic 
August morning would have needed a good deal o{ courage. Below them 
they could see the newly completed vault of the south tribune where, just 
three weeks earlier, a stonemason named Donato di Valentino had fallen a 
hundred feet to his death. Another man had also died in the rush to finish 
the tribune so that work on the dome could begin in the summer. The 
Opera had paid for both funerals, but this was the extent of the charity 
that the men could expect. Anyone injured on the job would face a grim 
future, as would his family, because neither the Opera nor the Masons 
Guild made provisions for either disabled workers or the widows and 
children of dead ones. The only social obligation o{ the members of the 
Masons Guild was attendance at one another's funerals. 

Present in the minds of the stonemasons must also have been the 
awesome and abiding fact that none of them yet knew whether the 
structure could actually be erected according to Filippo's plan. Certain 
details of the cupola's design had been established, of course, in the 
twelve-point building programme adopted the previous month. The width 
of the inner dome, for example, was to taper like that of the Pantheon, 


Men Without Name or Family 

diminishing from seven feet at its base to just under five feet at the top. 
And the exterior shell — added to protect the inner one from the elements 
as well as to make the entire structure appear piu magnifica e gonjiante ('larger 
and more inflated*) — was to narrow from a width o^ slightly over two feet 
at its base to one just over a foot at the oculus. Likewise the eight vertical 
ribs at each corner of the octagon were to taper as they rose skywards. And 
while the dead load o^ the Pantheon had been lessened by the use of 
pumice-stone and empty bottles, in Santa Maria del Fiore the shells were 
to be built out of stone for the first 46 feet, then from either brick or tufa, 
the latter being a light, porous stone formed from volcanic ash. The 
building programme also outlined, albeit vaguely, the incorporation o^ a 
number of rings o( sandstone beams held together with cramps of leaded 
iron — the chains that Neri di Fioravanti had envisioned encircling the 
dome's circumference. These would be embedded in the masonry and, 
therefore, hidden from view. 

It was the twelfth point that raised the most doubt. The wardens agreed 
that for the first 30 hraccia of their height — that is, for a distance of about 
57 feet above the drum — both shells were to be built without any scaffold- 
supported centring. Thereafter, from 30 hraccia upwards, the dome was to 
be built 'according to what shall then be deemed advisable, because in 
building only practical experience will teach that which is to be followed'. 

This vital condition reveals the reservations of the wardens in the face 
of Filippo's daunting plan. Acceptance o^ it represented a concession on 
Filippo's part, a means of appeasing the nervous wardens by committing 
himself to building only the first fifth o{ the dome without centring. If he 
succeeded, he would then have to make his case to raise the rest o{ the 
cupola in similar fashion. F^e must have felt frustrated by the wardens' 
continuing lack of faith, but he may also have felt relieved that he was 
given some time to consider his plans. It is conceivable that even he was 
unsure o^ himself at this early stage. Uncertainty about how to execute his 
audacious plan, and not simply fear oi someone stealing his ideas, may 
have been one of the reasons why he refused to divulge to the incredulous 
wardens the secret behind the procedure of vaulting without centring. As 


Brunelleschi's Dome 

late as the summer of 1420, for example, he had still to work out the 
design of the circumferential stone chains. He would not in fact devise a 
plan for the first one until June of the following vear, barely a month 
before its construction was due to begin. And plans for the second were 
not completed until 1425, when yet another model had to be made. 

Neither Filippo's brick model of the dome nor the cupolas he built for 
the two chapels could quite have prepared him for the task ahead. It had 
long been known that architectural models were poor guides to statics, 
because what worked structurally in a model could not necessarily be achieved 
when the proportions were magnified. In the Middle Ages and Renaissance, 
proportionally identical models behaved differently depending on their 
respective sizes, and scale models were generally misleadingly strong.* 

Given the experimental nature of Filippo's plan, the 30 hraccia limit 
seems to have been a wise precaution, especially since a sound logic 
governs the restriction. At a height of 30 hraccia the bed joints of the 
masonry would have risen to form an angle of 30 degrees to the horizontal, 
or just inside the critical angle of sliding. Friction alone would keep the 
stones in place up to an angle of 30 degrees, even when the mortar was 
green; therefore, no centring would have been required until that point. 
Above that level, however, each course of masonry would incline more 
sharply, reaching a maximum angle, near the top, of 60 degrees to the 
horizontal. No doubt it was impossible for the wardens to imagine how 
these courses might be held in place without centring of some sort. 

Both Filippo and the wardens seemed to be purchasing themselves a 

* Vitruvius describes the problem in an anecdote about an engineer named Callias who 
designed a model of a revolving crane which was to be set on the walls of Rhodes and used 
to capture enemy siege engines. The model itself functioned perfectly well but the enlarged 
version did not, forcing the Rhodians to resort to the old-fashioned method of pounng 
rubbish and excrement over the heads of their besiegers. Nor were such difficulties in scalmg 
up designs limited to ancient or medieval times. In the late 1980s the Pentagon encountered 
just this problem when it expanded one of its successful designs — the Trident 
intercontinental ballistic missile — only to discover that the end product, the Trident z missile, 
had the flaw of triggering its own self-destruct mechanism four seconds after leaving the 


Men Without Name or Family 

little time by deferring the central question of how the dome should be 
vaulted. All were agreed that, in an unprecedented structure like the dome, 
any constructional difficulties could be solved, as the 1420 programme 
stated, only by means of 'practical experience'. This was perhaps to err on 
the side of optimism. But just such a process of trial and error was about 
to begin. 


Some Unheard-of Machine 

I am accustomed, most of all at night, when the agitation of my soul fills me with cares, 
and I seek relief from these hitter worries and sad thoughts, to think ahout and construct 
in my mind some unheard-of machine to move and carry weights, making it possible to 
create great and wonderful things. 

These words are spoken by the statesman Agnolo Pandolfini in a 
philosophical treatise written by one o^ Filippo's ablest disciples, the 
architect and philosopher Leon Battista Alberti. Delia tranquillitd deWanimo 
('On the Tranquillity of the Soul') was composed in 1441, a few years after 
Filippo's dome had been completed. It features a dialogue between two 
men who have suffered miserably from changes in fortune: Agnolo, who 
has retired, disillusioned, from public life, and a younger man, Nicola de' 
Medici, whose bank has failed, leaving him destitute. Their conversation 
takes place inside Santa Maria del Fiore, under the new dome, and 
concerns the various means o{ overcoming depression. Agnolo lists a 
number of traditional remedies for raising the spirits, such as wine, music, 
women and sports. But his most effective tactic, he tells Nicola, is to 
fantasise about the construction of giant hoists and cranes that can be used 
to create 'great and wonderful things' — machines for raising magnificent 
structures, that is, like the dome that swells above them. 


Some Unheard-of Machine 

One of the most obvious problems in building the dome of Santa 
Maria del Fiore — or mdeed any large structure — was how to transport 
hea\T building materials such as sandstone beams and slabs of marble 
several hundred feet above the ground and then place them mto position 
with the accuracy demanded bv Filippo's design. The sandstone beams 
weighed some 1,700 pounds each, and hundreds of them needed to be 
raised on to the cupola. To solve this problem Filippo was compelled to 
imagine 'some unheard-of machine' to move and carr\' tremendous weights 
to incredible heights. The hoist that he created was to become one of the 
most celebrated machines of the Renaissance, a device that would be 
studied and sketched bv numerous other architects and engineers, 
including Leonardo da \^inci. And it was also, no doubt, the inspiration 
behind Agnolo's soothing fantasies. 

A number of machines were already in use on the building site, of 
course. Twenrv years earlier a rota magna, or 'great wheel', had been 
constructed to raise the hea\T stones used in the fagade, drum and tribunes 
of the cathedral. This machine, still operational in 1420, was a treadmill 
that winched loads aloft under the motive power of several men who 
walked around, hamster-like, mside a large wheel. Such devices had been in 
use since ancient times. In De architectura the Roman architect Vitruvius 
describes a treadmill turned by 'tramping men', presumably slaves. The 
treadwheel, a sort of giant spool, either wound or unwound a rope that, in 
passing through a system of pulleys, raised or lowered the weight attached 
to its end. The muscular effort involved m powering these winches was 
not excessive provided the loads were relatively light and the heights to 
which they were transported not especially high. 

Recognising that the rota magna would be woefully inadequate to the 
task of lifting heayy stones to the height required by the dome, the Opera 
del Duomo had specifically called for models of lifting devices in the 1418 
competition. But the models submitted m the ensuing months showed 
only the cupola or its centring rather than the machines for their 
construction. Two weeks after the appointment of the three capomaestri, the 
Opera was stiU referring in its documents to an intended plan of using a 


Brunellcschi's Dome 

plain treadmill — possibly the old rota magna — for hoisting the materials. 
Filippo must have found such a lack of enterprise appalling. He eagerly 
responded to the challenge and, in one of his first acts as capomaestro, began 
designing a machine that would be powered not by men but by the busiest 
and most prized beast of burden in the Middle Ages, that powerful but 
placid creature, the ox. 

Work on this new hoist started in the summer of 1420. For its parts 
Filippo contracted with a wide number of artisans, many of them from 
outside Florence. Several weeks after the celebratory feast on the tambour, 
the Opera received shipment of an elm tree from which the drums for the 
new hoist were to be hewn. The tree must have been enormous, because 
the largest of the three drums was five feet in diameter. Elm was chosen for 
its resistance to the elements, for clearly the hoist would need to be in 
service for many years. Other parts for the hoist had also begun arriving: 
chestnut poles for the building of the supporting frame and a harness and 
reins for the oxen. A rope was ordered from Pisa, a shipbuilding town 
where the art of rope-making was highly advanced. Still, Filippo's hoist 
must have taxed even rope-makers accustomed to fitting out the largest 
galleons, for it required one of the longest and heaviest ropes ever 
manufactured: 600 feet long and weighmg over a thousand pounds. 

Construction on the hoist continued throughout the winter of 1420—21. 
A blacksmith was engaged to make bearings for the pulleys of the hoist 
and a turner to cut cogs from ash wood for its wheels. Meanwhile a barrel- 
maker began making hoisting tubs to hold the loads of masonry and 
mortar on their ascents. Finally, two master carpenters were hired to build 
the frame and assemble the various parts. Each of them spent sixty-seven 
days on the job. 

Work must have proceeded at a furious pace, because in the spring of 
1421 the hoist took its place on the floor of the octagon. Or rather it took 
its place on a 29-foot-long wooden platform specially constructed for the 
oxen that were to make thousands of revolutions over the next dozen 
years. Before the dome was complete the hoist would raise aloft marble, 
brick, stone and mortar weighing an estimated 70 million pounds. 


8. A drawing by Taccola of BruneUeschi's ox-hoist, in this case being driven 
by a horse. At the bottom, the helical screw which raises and lowers the 

wheels is clearly depicted. 

Brunelleschi's Dome 

Filippo's ox-hoist was remarkable both for its sheer size and power, and 
for the complexity of its design, especially its reversible gear, an important 
innovation for which there is no known precedent in the history of 
engineering. In the words of one commentator, the machine was 'centuries 
ahead of the technical understanding of the time'.^ It consisted of a 
wooden frame, fifteen feet in height, to which were attached a number of 
horizontal and vertical shafts or spindles that rotated each other by means 
of cogged wheels of varying sizes. The machine was set in motion by either 
one or two oxen yoked to a tiller that turned the vertical shaft. This shaft 
or rotor was furnished with two cogged wheels, one at the top and another 
at the bottom, either of which could mesh with a much larger wheel on a 
horizontal axis. Only one of the wheels on the rotor could be engaged at a 
time, however: one to raise loads, the other to lower them. The change in 
gears was effected by a large screw with a helical thread. Turned in either 
direction, it would lift or drop the rotor several inches, thereby engaging 
one or other of its pinions with the teeth of a wheel attached to the sMio 
grosso, the largest of the three rope drums. 

This screw that raised and lowered the rotor was one of the hoist's 
most ingenious features. It served as a clutch, connecting or disconnecting 
the two gears from the wheel of the large drum. This meant that the hoist 
could be reversed — and loads either raised or lowered — without the driver 
being forced to unyoke the oxen and turn them round. The oxen, that is, 
only ever moved in a clockwise direction. The obvious benefit of this gear 
change was that a great deal of time was saved between each ascending or 
descending operation. Oxen were ideal for moving heavy loads, given their 
stamina and strength. But they could not be made to walk backwards more 
than a few steps, a reluctance that hampered any driver trying to unyoke 
them from the tiller. 

When one of the two pinions on the vertical shaft was in mesh with the 
cogs on the horizontal shaft, the gear train was set in motion. The large 
rope drum was attached to a medium-sized horizontal spindle, the sMio 
mezzano, which, through a secondary set of gearing at its opposite end, 
engaged another shaft, the suhhio minore, a smaller horizontal spindle 


Some Unheard-of Machine 

running parallel with the 
two other rope drums. Any 
o{ these three horizontal 
shafts — small, medium or 
large — could be used to 
raise or lower loads. 
Because of their varying 
diameters, however, each 
turned the rope at a "differ- 
ent rate of speed and 
required a different degree 
of effort from the oxen. 
The suhhio grosso, five feet in 
diameter, raised the load 
more quickly than the sikhhio 
minore, which was only 20 
inches in diameter and 
therefore forced the oxen 
to make many more revolutions for each ascent. This smallest shaft was 
used to raise the heaviest loads, much in the same way that a cyclist uses 
the smallest chain wheel to engage the bicycle chain on steep ascents. 
Using this shaft, one ox could raise a load of 1,000 pounds to an elevation 
of 200 feet in approximately thirteen minutes.^ 

Once inaugurated in the summer of 1421, the giant hoist must have been 
a marvel even in Florence, where the building boom of the previous fifty 
years meant the populace was accustomed to seeing machines raising 
skywards heavy loads of brick and stone. After being transported in a cart 
from the quarry to the building site, a sandstone beam weighing almost 
two tons would be slid into the octagon on elder-wood rollers that had 
been greased with tallow or soap. It was then attached to the hoist rope by 
means of a special hanger, the sort of mortise-and-tenon contrivance now 
known as a lewis bolt'. This hanger was yet another of Filippo's 
innovations, probably inspired by his study of Roman masonry. 

9. A detail of the ox-hoist which shows, on 
the right-hand side, the secondary 
set of gearing. 


Brunelleschi's Dome 

It required a rectangular hole a foot long to be cut into the top of the 
stone, then undercut several degrees such that it was dovetailed, narrowest 
on the surface and widest at the bottom. Next, the three iron bars 
comprising the hanger were mserted into the hole. The outside two were 
dovetailed in order to fit the mortise, while the middle one was flat. The 
outside bars were inserted first and then prevented from slipping out o{ the 
socket by the middle one, which would have been hammered into place, 
providing a tight fit. Finally, a crossbolt was slid horizontally through the 
eyes in the top of the three bars and the rope attached to it. The stone was 
then ready to be winched on to the cupola. 

Certain perils were inherent in the operation of the ox-hoist. Friction 
had to be minimised because the energy lost in friction created heat, which 
could easily start a fire, an obvious catastrophe if the beam was dangling in 
mid-air. And Filippo's enormous rope, with its cross section of some two- 
and-a-half inches, would have been in danger of combustion, for thick 
ropes with a great resistance to bending generate a lot of friction. Smooth 
walnut tubes were therefore used to encase the drums, and the rope was 
wetted with water in order to prevent it catching fire as it passed through 
the pulley wheels. Sea water, vinegar or spoiled wine were preferable to 
fresh water, which rotted the rope. 

Once the load reached the working level, a signal was shouted from the 
cupola and the oxen were halted. The rope was detached from the 
crossbolt and, far below, the clutch screw was turned, changing the gear. 
The oxen trudged forwards again, unspooling the rope from the drum, 
which now rotated in the opposite direction, bringing the rope back down 
to the floor of the octagon, where it would be attached to another lewis 
bolt that in the meantime had been secured to the next sandstone beam. 
The whole operation would then begin all over again. It must have run like 
clockwork, for the hoist raised, on average, fifty loads per day, or roughly 
one every ten minutes. 

The exact inspiration for this remarkable machine remains as 
mysterious as that behind Filippo's other inventions. The specialist 
theoretical knowledge needed for constructing such a hoist was largely 


Some Unheard-of Machine 

unavailable in 1420, though soon afterwards a number of manuscripts on 
Greek mechanics and mathematics began arriving in Florence, putting 
architects and inventors of the Renaissance in possession of engineering 
techniques far beyond those available in the Middle Ages. In 1423, two 
years after Filippo finished buildmg his hoist, a Sicilian adventurer named 
Giovanni Aurispa returned from Constantinople with a hoard of 238 
manuscripts written in Greek, a language that scholars in Italy had learned 
only in the previous few decades. Among these treasures were six lost plays 
by Aeschylus and seven by Sophocles, as well as works by Plutarch, 
Lucian, Strabo and Demosthenes. But there was also a complete copy o{ 
the works of the geometer Proclus of Alexandria and, even more important 
for engineers, a treatise on ancient lifting devices, the Mathematical Collection 
of Pappus of Alexandria. This latter work, from the fourth century AD, 
describes the windlass, the compound pulley, the worm and wheel, the 
screw and the gear train — all essential features of hoists and cranes. In the 
decades that followed, so many manuscripts on Greek mathematics and 
engineering emerged that it is possible to speak of a 'renaissance of 
mathematics' in fifteenth-century Italy.^ 

All of these discoveries came too late to help Filippo with his ox-hoist. 
In any case the capomaestro, like Shakespeare, knew little Latin and less 
Greek, so these manuscripts would have been of slender value to him 
unless they were first translated into Italian.'^ Filippo therefore probably 
knew about the workings of pulleys, clutches and gear trains not through 
old parchments but, rather, from his own experience. Growing up only 
several hundred yards from the cathedral he saw in almost daily operation 
what Manetti calls 'a variety and multitude of different devices': treadmills 
and cranes built under the direction of previous capomaestri, including 
Giovanni di Lapo Ghini, who in the 1350s devised a treadwheel for 
winching masonry to the vaults of the nave. Still, however much they may 
have stimulated Filippo's youthful imagination, these machines would have 

* That Filippo read no Latin — or very little, at any rate — is known because of the fact 
that in 1436 Alberti translated De ptctuira, his work on perspective, into Italian so that his 
master could read it. 


Brunelleschi's Dome 

been unsophisticated in comparison to the ox-hoist, consisting simply of 
shafts and wheels that moved a rope over a system o£ pulleys. It is unlikely 
m the extreme, for mstance, that any of them included complex meshing 
parts such as those featured in his own hoist, let alone prototypes of the 
motion-reversing clutch. 

Manetti also suggests another inspiration for the ox-hoist. He claims 
that Filippo, while still a young goldsmith, built a number of mechanical 
clocks equipped with Various and diverse generations of springs'. If this 
story is true, these devices would have been as far ahead of their time as 
the ox-hoist. AU mechanical clocks during this period were driven by a 
falling weight attached to a cord spooled round a drum. As the weight 
descended it unwound the cord and turned the drum, which then rotated a 
wheel whose teeth — like those on the wheel of the ox-hoist's suhbio grosso — 
engaged the pinions and gears of the driving-train, the motions of which 
were regulated by an escapement. But Filippo's clocks, according to 
Manetti, used springs instead of weights to drive their gear-trains — an 
astonishing claim, since spring-loaded clocks are not known to have been 
invented for almost another hundred years. Indeed, elastic springs of the 
sort needed for such clocks were not developed until many decades later, 
when metallurgical techniques were refined enough that it became possible 
to manufacture resilient wire. 

Apart from Manetti's claim, no evidence exists for these spring-driven 
clocks other than an anonymous sketch done later in the century, possibly 
based on a design by Filippo's friend Mariano Taccola, who is known to 
have drawn a number of the capomaestros inventions. It is plausible, however, 
that Filippo's experimentations with clock mechanisms, with cog-wheels 
and counterweights, served him when the time came to design his ox-hoist.' 

Whatever its inspiration, the hoist inspired great confidence from the 
start. As soon as it was finished, Filippo pressed the Opera for a prize, 
mindful that no one had so far received the 200 florins promised in the 
1418 proclamation. Within a month a substantial award of 100 florins was 
granted to him 'for his ingeniousness and labours in connection with the 
device newly invented by him for hoisting'. In what now seems like a 


Some Unheard-of Machine 

\m\ ^ 

lo. A drawing of a spring-driven clock, possibly based on one 
of Brunelleschi's designs. 

classic understatement, the Opera commended him for the design o{ this 
hoist, 'which is more useful than the one previously employed'. 

The ox-hoist had been designed to raise heavy loads far into the air with 
maximum speed and efficiency. In this task it probably excelled any hoist 
ever constructed, for one or two oxen were able to raise loads that before 
had taken as many as six pairs. But this remarkable machine none the less 
shared the shortcoming of all hoists: devised only to raise or lower 
burdens, it was unable to move them laterally. Yet sideways motion was an 
obvious requirement for laying the beams for the stone chains. These 
beams were interlocking and, at several levels, radially tilted towards the 
vertical axis of the dome. A machine capable of shifting them infinitesimal 
distances in any direction — up, down or sideways — was therefore required 
so they could be laid in place with pinpoint accuracy. 

Since 141 3 a crane known as the Stella had been used for the vaulting of 


Brunelleschi's Dome 

the tribunes. But ten years later this machine, Hke the rota magna, was no 
longer adequate for the greater demands of the cupola. A more powerful 
crane with a longer working arm was needed. And the Opera del Duomo 
met this challenge in typical fashion: it proclaimed yet another 
competition, asking for designs to be submitted by April 1423. 

The winter o{ 1422—3 proved to be a hard one. The tramontana, a raw 
wind that, according to folklore, brought depression and fatigue to 
Florence, howled down from the Apennines. In January work on the 
cupola stopped because of the cold and a network of boards had to be 
placed over the walls to protect them from snow. Filippo took advantage 
of this hiatus in order to devise a crane for the competition. Given the 
success of the ox-hoist, the result of the Opera's deliberations could have 
surprised no one: in April the wardens selected his design over one 
submitted by a rival, Antonio da Vercelli, whom Vasari implies was a 
creature that Lorenzo Ghiberti thrust forwards in the hope of challenging 
Filippo's expertise and thwarting his authority. 

Within a few days the wood for Filippo's machine began arriving at the 
building site: eight pine beams, along with two elm trunks, each 15 feet 
long. Then a walnut tree was delivered from which the crane's screws 
would be carved. As with the ox-hoist, the machine was built in a 
remarkably short time, less than three months, and was ready by the 
beginning of July. 

Known as the castello, this new crane consisted of a wooden mast 
surmounted by a pivoted horizontal beam. Sitting high on the cupola, it 
must have resembled a gallows. The horizontal crossbeam was furnished 
with screws, slideways and a counterweight. One of the horizontal screws 
moved the counterweight along the slideway, while the other manipulated 
the load, which could also be raised or lowered by means of a turnbuckle. 
This turnbuckle permitted the installation of the stone with far greater 
control than the ox-hoist, whose driver, several hundred feet below, relied 
on shouted commands from the cupola. 

The castello would go into operation as soon as the ox-hoist delivered the 
stone to the working level. Standing on a small platform at the top of the 


Some Unheard-of Machine 


II. A drawing by Buonaccorso Ghiberti of three turnbuckles and, 
inset, a lewis bolt to attach a piece of stone to a hook. 

crane — one of the giddiest and most dangerous of all of the stations on the 
cupola — the operator turned the horizontal wooden screw that moved the 
load laterally through the air beneath the crossbeam. At the same time, the 
counterweight at the other end of the beam was adjusted m order to keep the 
crane in equilibrium. A horizontal arm projecting from the mast prevented 
the load from swinging at the end of the rope — a danger in the high winds that 
swirled round the cupola. Then, once the stone was hovering above its final 
destination, the turnbuckle was adjusted and the load descended into place. 
The success of the castello is remarkable given the lack of understanding 
of the strength of materials at the time. Other than through precedent, 
Filippo had no way of knowing the robustness of his crane's long 
horizontal beam when placed under the stress of a heavy load. Not until 
the studies of the French engineer Claude-Louis Navier in 1813 was the 
bending strength of beams mathematically determined. In 1420 calculations 


12. Leonardo da Vinci's drawing of the castello. 

Some Unheard-of Machine 

were based on ancient theories about the various 'humours' of trees in the 
same way that the medicine of the day — equally suspect — was concerned 
with the interaction of humours in the body. Elm, for example, the wood 
used in the crossbeam, was said to be 'dry', therefore it did not 'agree' with 
the plane tree or the alder, which were 'moist' and so ought never to be 
used in the same structure as elm — a most dubious set of assumptions on 
which to rest a sandstone beam weighing over i,ooo pounds. The sight of 
one of these heavy stones dangling at the end of a crossbeam must have 
been, mitially at least, an unnerving sight. 

But the crossbeam held and the castello, like the ox-hoist, needed only 
minor repairs in the decade that followed. Indeed, in one respect the castello 
was to prove too durable. Like the ox-hoist, it remained on the cathedral's 
building site through the 1460s, long after Filippo's death, and was present 
during the last act of the dome's construction: the placement of the eight- 
foot-high bronze sphere that sits atop the lantern. The commission for 
this bronze ball went to the sculptor Andrea del Verrocchio, in whose 
workshop there was at this time a young apprentice named Leonardo da 
Vinci. Fascinated by Filippo's machines, which Verrocchio used to hoist 
the ball, Leonardo made a series of sketches of them and, as a result, is 
often given credit for their invention. How Filippo would have reacted to 
this misattribution — Filippo, who was so proud of his inventions and so 
fearful of plagiarism — scarcely bears contemplation. 


The Chain of Stone 

No SOONER WAS the ox-hoist finished than plans began moving 
ahead for the first sandstone chain, and in early June a design fi3r 
the chain had finally been settled upon: a carpenter working for 
Filippo, a man named Jacopo di Niccolo, was paid for a wooden model 
demonstrating how the beams would be linked. This chain was complex in 
design, consisting of two concentric rings of stone laid horizontally around 
the octagonal circumference of the dome. These long beams rested on, and 
interlocked with, shorter beams laid transversely, like railway sleepers, at 
intervals of ever\' three feet. Before June was out, some eighty-six cart-loads 
o{ sandstone had arrived in the Piazza del Duomo from the Apennines. 
Seen from either the dome or the campanile o{ Santa Maria del Fiore 
the hills surrounding Florence have the sensuous contours of a supine 
body. Dozens of quarries were worked on their slopes during the 
Quattrocento, including several near the village of Settignano, the 
childhood home of Michelangelo, whose wetnurse was the wife of a stone- 
cutter and, according to the sculptor, the source of his genius with 
hammer and chisel. The hills are formed from macigno, a quartz-bearing 
sandstone so hard that during the Middle Ages it was favoured for 
grindstones. In Florence it was also used in the construction of buildings. 
So abundant were its seams that all one had to do to build a house 


The Chain of Stone 

I I I I I 


. sS^^ 

V^ ^ \ C T 

^ X circumrerential 

stone beams 


stone beam 

13. The sandstone chain. 

in Florence, it was said, was to 
dig a hole and then pile up the 
stones. Several quarries were 
actually found within the city 
gates, between the convent of 
Santa Felicita and the Porta 
San Piero in Gattolino (now 
the Porta Romana); one of 
them was even owned by the 
convent's nuns. The Arno also 
provided the city with sup- 
plies o'l stone: a limestone 
known as lapidum Arnigerum 
was quarried along its south 
bank. But the stone for the 
circumferential chains would 
come from the Cava di Tras- 
sinaia, a quarry a few miles north o( the city, near the ancient town o{ 
Fiesole. Work sheds were erected on the site in March 1421, and soon 
afterwards a team o^ nineteen stonemasons went to work. 

Most stonemasons served their apprenticeships m the quarries, learnmg 
from their masters how to recognise the best beds of stone, how to cut 
with or against the grain, and how to dress them according to the 
architect's templates. The extraction and shaping oi a stone made for 
strenuous labour. A saw was first oi all used to cleave the stone from the 
hillside. In the case of a hard stone like macigno, mixtures of sand and iron 
filings would be sprinkled under the teeth of the saw to act as abrasives 
and compensate for the comparative softness of the metal. Prised free with 
a crowbar and wooden wedges, the stone was cut roughly to size with a 
pickaxe and afterwards dressed using a hammer with a lighter blade. It was 
then sounded as a test of its quality — that is, struck lightly with a hammer. 
If there were no flaws, the stone would ring like a bell, whereas a dull thud 
indicated a crack or some other defect, and it would be discarded. Another 


Brunelleschi's Dome 

test of quality- was the smell. Freshly cut from a quany-, limestone and 
sandstone smell of rotten eggs, and the stronger this sulphurous stench, the 
better the quality of stone. 

The dimensions and shapes of the stones needed for Filippo's chains 
were highly particular. Each of the long circumferential beams had to be 
7/2 feet long and 17 inches in section. Furthermore, each stone was to 
have a series of notches cut into its underside so it could interlock with the 
shorter beams laid transversely beneath. The first sandstone chain used 
over a hundred of these long beams and almost as many of the short ones. 

Templates, either drawn on parchment or carved from wood, were used 
as guides for dressing the stone. But because of the complexity of Filippo's 
design, the stonemasons had difficulty understanding how exactly the 
stones were to be cut and then fitted together. The enterprising capomaestro 
therefore made other, less conventional models for them to follow. A 
number of these were made from wax and clay, and some he even carved 
from rape grandi, large turnips that the Florentines ate in winter. 

To function effectively the circumferential stones, which met at 45- 
degree angles, needed to be linked tightly together at their ends. This was 
achieved by iron clamps that coupled them together. Filippo travelled to 
Pistoia to oversee the casting of these clamps, which were so specialised 
that the ironmongers, like the stonemasons, could barely understand what 
was required of them. Once forged, these clamps were glazed with lead to 
prevent the iron from rusting and therefore causing the surrounding 
masonry to crack. Many thousands of pounds of lead were used for 
rustproofing both these clamps and the iron bars installed elsewhere in the 
cathedral. Plumbers (whose name comes from the Latin plumbum, 'lead') 
were employed at most cathedrals in the Middle Ages in order to 
rustproof iron or make lead tiles for the steeples. Such a recourse, 
naturally, meant one more danger for the workers at Santa Maria del Fiore, 
for it had been known at least since the time of the Romans, when the 
architect Faventinus observed the 'deformity' and 'dreadful anaemic pallor' 
of plumbers, that lead was a poisonous metal. 

The sandstone chain was only the first of four to be laid, part of a 


The Chain of Stone 

system of four bands that would encircle the dome at regular intervals of 
35 feet. In the spring of i^z^ Filippo executed a model for the second 
chain, which was even more complex than the first because the transverse 
beams were radially disposed, like a set of spokes, towards the vertical 
centre or 'hub' of the dome. Also, they were inclined at an angle rather 
than laid horizontally, a process that would require the expertise of the 
new castello as well as, we shall see, an extremely precise system of 

The Opera's documents record that the sandstone beams were to be 
superimposed by continuous iron chains. Iron has a far higher tensile 
strength than sandstone, meaning that the iron chains encircling the dome 
would actually have provided most of the resistance to the horizontal 
thrust. However these chains, so essential to the dome's success, are also 
one of its secrets: it is impossible to know their composition, for the 
simple reason that all of them are embedded in the masonry and therefore 
hidden from view. There is no reason to assume that they were not 
installed, but a magnetic survey conducted in the 1970s failed to detect any 
evidence of them. 

The sandstone chains are not the only circumferential ties in the dome. 
They were supplemented by a fifth, made of wood and installed in 1424, 
which encircles the dome 25 feet above the first stone chain. Four of these 
wooden chains were originally planned, but in an example of how 'in 
building only practical experience wiU teach that which is to be followed', 
only the first was ever executed. 

The wooden chain created problems for Filippo from the start. The 
programme of 1420 had specified that it should be made from beams of 
oak 20 feet in length and a foot wide. But a year later, when sufficient 
quantities of oak proved hard to find, chestnut was chosen instead. In aU, 
twenty-four beams would be needed, three on each side of the octagon, 
and they would be spliced together with clamps made from oak. Although 
the chestnut beams were ordered in September 1421, as the first sandstone 
chain was being laid, they would not arrive until more than two years later 


Brunelleschi's Dome 

— no doubt a discouraging sign to anyone still dreaming of erecting the 
structure with a large wooden centring. There was, first of all, the problem 
of finding chestnut trees of an adequate diameter. Then, once the timber 
was found, it had to be felled in accordance with various rules and 
traditions, such as waiting for the wane of the moon, since wood cut at 
this time was thought less apt to breed worms. And once felled, it had to 
be properly seasoned, a time-consuming operation. First of all, its sap was 
driven off by soaking the wood in water for up to a month. Alternatively, 
the timber would be buried for several weeks in ox dung, in much the 
same way that animal hides were tanned with manure. The wood was then 
placed on a bed of ashes or bracken and exposed to the air, but protected 
from the rain and sun, for anything up to several years. Given these various 
procedures, it is little wonder that Filippo faced such a wait. 

Like the four stone and iron chains, the wooden chain was no doubt 
part of Filippo's system of invisible buttressing, a means of containing the 
hoop stress of the dome, for wood, like iron, has a greater tensile strength 
than sandstone. It may even have been intended to protect against a 
particularly violent kind of stress. A similar series of wooden ties were 
incorporated into the base of the dome of Santa Sophia in Constantinople, 
at the point where the greatest tension would develop, while more timber 
bonds were introduced into the brickwork following the earthquake of AD 
557." Likewise, a double ring of poplar beams embraces the dome of the 
tomb of Oljeitii at Sultaniya, put there to counteract damage caused by the 
earthquakes on the Plateau of Persia. 

Did Filippo have a similar form of protection in mind when he 
designed his wooden chain? Manetti alludes to 'hidden devices' that were 
placed inside the dome to protect it from both the wind and earthquakes. 
Wind loading (the force exerted on the dome by the wind) was not of 
particular consequence, because of the sheer size of the structure. 
Earthquakes, on the other hand, were a factor. Quakes would strike the 
city in 1510, in 1675, ^^^ again in 1895. The shocks from the first of these 
were so severe that many people spent the ensuing nights camped in the 


The Chain of Stone 

open air of the piazzas rather than returning to their homes. None of these 
earthquakes, however, caused damage to the cupola. 

There may also have been another reason for the timber chain: a 
political rather than a structural one. It appears to have been, at least m 
part, an elaborate intrigue on the part of capomaestro Brunelleschi, a means 
of undermining the authority of Lorenzo Ghiberti by exposing his 
ignorance in matters of architecture and engineering. For, several years into 
the buildmg of the cupola, the battle between the two capomaestri was about 
to explode. 


The Tale of the Tat Carpenter 

THE RIVALRY BETWEEN Filippo and Lorenzo had been 
simmering for several years. Although the two men had been 
appointed as equals, Filippo had swiftly eclipsed Lorenzo. After 
the ox-hoist was built and the first stone chain laid, he was referred to in 
the documents as the inventor et ghuhernator maior cupolae, a title mdicating 
how he had risen above his colleagues. Filippo's mandate, according to the 
wardens, was to 'provide, arrange, compose or cause to have arranged and 
composed, all and everything necessary and desirable for building, 
continuing and completing the dome'. Lorenzo, by contrast, was merely to 
'provide' towards this end. So it must have irritated Filippo to know that 
Lorenzo was not only enjoying the same salary — 3 florins per month — but 
likely to share the credit for Filippo's ingenuity. 

The wooden chain afforded Filippo the opportunity of discrediting his 
colleague. Models for this chain had been designed by Filippo as well as 
by the two other men, including Giovanni da Prato. A prize of 100 gold 
florins was at stake. In August 1423 Filippo's design was selected by the 
wardens, yet another victory for the capomaestro, whose reputation was 
looming ever larger. But when the chestnut trees finally arrived in Florence, 
disaster seemed to strike: Filippo took to his bed, complaining of a pain in 
his side. He lingered there for several days, and when he was finally 


The Tale of the Fat Carpenter 

induced to return to the building site he did so only with his head 
bandaged and his chest poulticed. This theatrical display managed to 
convince many people that Filippo was at death's door. Others believed he 
was malingering, and soon rumours were bruited about Florence that his 
mysterious illness was actually a lack of nerve, an inability to follow 
through on his grandiose and impossible plan. The invalid made no 
response, merely shuffling back to his sick-bed. 

Responsibility for building the wooden chain — and for raising the 
dome — therefore fell to Lorenzo. This enormous obligation caused the 
goldsmith no small amount of disquiet, for Filippo, true to his nature, had 
not made his colleagues privy to the structure of the wooden chain, let 
alone the ultimate design of the dome. But it was Filippo's model for the 
chain — one as confusing to the uninitiated as all of Filippo's models — 
that Lorenzo suddenly found himself charged with reproducing. 

Work on the site ground to a halt as the stonemasons and carpenters 
awaited their instructions. Filippo was requested to return to the site and 
offer his advice. But the condition of the capomaestro was deteriorating so 
swiftly that great alarm was aroused in the Opera. Finally, afraid of 
exposing his ignorance, Lorenzo bade the men resume, and under his 
direction they began laying the chestnut beams along one of the eight walls 
and fastening them together. 

Interconnecting these logs was an important and complicated task. 
Lorenzo proceeded in this operation as best he could, basing his design on 
the wooden chain that embraces the dome of the Baptistery. But Filippo's 
model called for a more complex design in which the logs would be 
clamped together with special plates made from oak. These had to be 
attached both above and below the junctions of the logs by iron bolts. The 
logs would then be wrapped in iron straps to prevent the bolts from 
splitting them. 

As soon as three beams had been connected along one wall, Filippo 
made a miraculous recovery. He rose from his deathbed, spryly ascended 
into the cupola, inspected Lorenzo's work and then began a whispering 
campaign against Lorenzo, declaring his oak fastenings worthless and 


Brunelleschi's Dome 

claiming that all three logs would have to be removed and replaced with a 
more effective construction — one that was ultimately executed under his 
own supervision. Thus, whatever its structural function, the wooden chain 
ultimately became a means for Filippo to expose Lorenzo's incompetence 
to both the wardens and the people of Florence. 

Filippo found himself rewarded for this intrigue a short time later: his 
salary was almost tripled, to loo florins per year. Lorenzo's remained at 36 
florins until the summer o{ 1425 when his pay was suddenly suspended. No 
further wooden chains were built. But \{ Filippo thought he had subdued 
Lorenzo and his deputy, Giovanni da Prato, he was sorely mistaken. 

If Filippo's illness was indeed feigned, it was not the first time he had 
played an elaborate trick on an unwary party. He was well known in 
Florence for his talents in mimickry, chicanery, theatricality and the 
creation of illusions. His most famous bit of trickery was a complex and 
ingenious hoax perpetrated against a master carpenter named Manetto di 
Jacopo. The story, known as 'The Tale o{ the Fat Carpenter', gained the 
status of legend in Florence and is related by Filippo's biographer, Antonio 
Manetti. An example of a hejja, a cruel and humilating trick, it is worthy 
o'i the pen o{ ^occ'^iccxo and anticipates the topsy-turvy dreamworld into 
which the characters are plunged in Shakespeare's A Midsummer Night's 

The hoax took place in Florence in about 1409, during one o{ Filippo's 
returns from Rome. The victim was a carpenter named Manetto, known as 
// Crasso, or the Tat Man'. Manetto specialised in carving ebony and 
owned a shop in the Piazza San Giovanni, not far from Filippo's house. 
He was prosperous and good-natured, but one day had the misfortune of 
incurring Filippo's ire after missing a social gathering. Never one to resist 
retaliation, Filippo resolved to exact his revenge for this perceived slight by 
persuading a wide cast of characters to convince Manetto that he had 
metamorphosed into someone else: a well-known Florentine named 

As Manetto closed his shop one evening, Filippo went to his house near 


The Tale of the Fat Carpenter 

the cathedral, picked the lock, slipped inside and barred the door behind 
him. When Manetto arrived a few minutes later, he rattled the door and 
then, to his alarm, heard what sounded like his own voice (in fact, Filippo 
doing an impersonation) ordering him to go away. This impersonation 
was so convincing that he retreated in bewilderment into the Piazza San 
Giovanni. There he met Donatello, who inexplicably addressed him as 
Matteo, and shortly afterwards a bailiff, who likewise hailed him as 
Matteo and then promptly arrested him for debt. He was taken to the 
Stinche prison, where his name was entered in the gaol book as Matteo. 
Even his fellow prisoners — all of them party to Filippo's prank — 
addressed him by this alien name. 

The carpenter spent a sleepless night, fretting over events but solacing 
himself with the thought that he was merely a victim of mistaken identity. 
This comfort evaporated the next morning when two strangers — the 
brothers of the real Matteo — arrived at the prison and claimed him as 
their kin. They paid his debt and liberated him, though not before 
chastising him for his supposed gambling and profligate living. More 
bewildered now than ever, he was escorted to Matteo's home on the other 
side of Florence, near Santa Felicita, where his protests that he was not 
Matteo, but Manetto, appeared to fall on deaf ears. Over the course of an 
evening he almost became convinced that he had indeed metamorphosed 
into someone else. Fie was then put to sleep with a potion supplied by 
Filippo and carried, unconscious, back across the river to his own home. 
F^e was laid on his bed in a reversed position, with his head at the foot 
and his feet at the head. 

Awakening many hours later, the poor carpenter was confused not 
merely by his position on the bed but also by the disarray of his house, for 
his tools had been completely rearranged. His perplexity grew with the 
arrival of Matteo's brothers. These two men now treated him differently, 
greeting him as Manetto and relating the curious story of how the previous 
evening their brother Matteo conceived the fantastic notion that he was 
someone else. The story was soon confirmed by Matteo himself— the real 
one — who arrived at Manetto's house to describe his puzzling dream of 

Brunelleschi's Dome 

having been a carpenter. The disarray of the house was explained by the 
fact that in his dream Matteo noticed how his tools were out of order and 
in need of rearrangement. Faced with this evidence, Manetto became more 
convinced than ever that, for a while at least, he had exchanged identities 
with Matteo — in the same way that their names, so close in spelling, could 
be shuffled together and confused. 

This practical joke confused art and life in the same manner as the 
perspective panel that Filippo would paint a few years later. Just as he 
showed the viewer of the painting a clever fabrication that tricked him into 
mistaking the artificial for the real, he fashioned a unique perspective for 
Manetto by reordering and controlling his perceptions. Like the viewer 
peering through the peephole, Manetto could not know whether what he 
experienced was the 'real scene' or only a convincing but none the less 
distorted mirror image of that reality. Coincidentally, the perspective 
panel, which featured the Piazza San Giovanni, may even have included a 
representation of Manetto's shop. By that time, however, the unfortunate 
carpenter had left Florence, humiliated and confused. After the trick was 
exposed, Manetto emigrated to Hungary, where he successfully plied his 
trade and — in what makes a happy ending to the story — amassed a 
considerable fortune. 


The Pointed Fifth 

IN AD 148 THE ROMAN hydraulic engineer Nonius Datus was sent to 
the town of Saldae in Algeria and instructed by its governor to build 
an aqueduct through the middle of a mountain. Nonius duly surveyed 
the mountain, executed plans and cross-sections, calculated the axis of the 
tunnel and then supervised two gangs of experienced tunnellers as they 
began their excavations, each at a different end. Thereupon he returned to 
Rome, satisfied that the operation was progressing smoothly. Four years 
later, however, he received an urgent summons to Saldae. Upon arriving he 
discovered the population of the parched town in a despondent mood: the 
two teams excavating the tunnel had each accidentally deviated to the right 
and therefore failed to meet in the middle. Nonius managed to rectify the 
situation, but had he arrived a little later, he observed, the mountain would 
have possessed two tunnels instead of one. 

This anecdote is related in On Aqueducts, a work written by Sextus Julius 
Frontinus, the chief water engineer of Rome and one-time governor of 
Britain. Lost for many centuries, the treatise was discovered at Monte 
Cassino in the 1420s by the manuscript-hunter Poggio Bracciolini. The tale 
of Nonius and his errant tunnellers must have been a source of chastening 
reflection for the builders of the cupola, who had been faced with a similar 
constructional problem — that is, how would it be possible for eight teams 


Brunelleschi's Dome 

of masons, each working on one side of the dome, to raise their separate 
walls so that they would all converge at the top? 

One of the keys to raising the dome was the precise calculation and 
measuremenTofTiich horizontal layeFoFbrick or stone as it was added in a 
■gradually contracting sequence. But how would these measurements be 
taken? How could the curvature of the eight mdividua l walls be controlled 
during the process of construction? The difficulty was made even more 
acute by the fact that each wall had to incorporate two shells rising in 
tandem, as well as their supporting ribs. A deviation of only several inches 
in one o{ these ribs — each of which was over loo feet in length — meant 
that the connection, like that at Saldae, would not be achieved. 

The teams of masons at work on the dome had certain basic measuring 
devices at their disposal. Most of these had not changed significantly for a 
thousand years. For checking the perpendicularity of walls, for example, 
they used plumb-lines: a string on which a weight, usually a ball of lead, 
was suspended. The string would be braided like a fishing line in order to 
prevent the weight from rotating in the breeze. And to ensure the stones 
were laid in perfectly horizontal courses or layers, a mason's level was 
employed. This instrument was shaped like the letter A: a plumb-line hung 
from its apex, while the horizontal cross-piece was inscribed with a 
graduated scale. The plumb-line would come to rest in the centre of the 
cross-piece when the stone or brick was on a level plane. 

As they are neither perpendicular nor horizontal, vaults such as arches 
and domes obviously demanded a more complex system of measurement. 
The master builders of the Gothic cathedrals regulated the curvature of 
such structures by first plotting them full-scale, like a giant set of 
blueprints, on to special tracing-floors. These floors were covered in 
plaster of Paris on to which life-sized geometrical designs of, say, a vault's 
ribs would be drawn. Once these drawings were complete, carpenters used 
them to devise the wooden templates from which the stone for the ribs 
was shaped by the masons working at the quarry. The gypsum floor was 
afterwards wiped clear and the next set of drawings incised into its surface. 
If facilities for tracing-floors did not exist, an area of ground would be 


The Pointed Fifth 

cleared and the designs sketched in the soil. In 1395, for example, the plan 
for the timber trusses of the roof at Westmmster Hall were set out on a 
patch of ground near Farnham in Surrey. 

It was this latter method to which Filippo resorted m the summer of 
1420. Downstream from Florence he had a large area of the Amo's bank 
levelled, an expanse roughly half a mile in every direction, and in the sand 
he traced a full-scale plan of the dome.^ It is most likely that the templates 
for each of the eight vertical ribs were made from this enormous 
geometrical design. These models, cut from pine, were S/, feet in length 
and roughly 2 feet wide, bheets of iron were used to stiffen them and 
prevent their warping. They were fitted on to the outside wall of the inner 
shell, allowing them to serve as guides for both shells, which were built 
with identical inclinations. Moved progressively upwards as the dome rose, 
they en^ Ull^d lli^L diL LJ^lii iiuaajvl iibs vvuuld ulLim ately converge a t the 
l evel of the fourth stone rinp. In order for these ribs to serve as guides for 
the rest of the dome's vertical curvature, they were built first: that is, only 
after several courses of the bricks for the ribs were laid did the masons 
begin filling in the intermediate sections. 

Regulating the curvature of the ribs was not the only problem that 
confronted Filippo and the master masons. The cupola's bricks were not 
laid in horizontal courses but rather at ever incre asing angles to the 
horizontal plane, with the final layers leaning inwards at a steep 60-degree 
angle. A method therefore had to be found of guidingand controlling this 
gradual inclination. A related difficulty was calculating SFTe radial 
dispositions not only of the bricks but also the transverse sandstone beams 
of the second and third stone chains: all of this masonry had both to tilt 
inwards as well as to radiate from the vertical centre of the dome. Under 
such circumstances, traditional tools such as plumb-lines and mason's 
levels were quite useless. 

F^ow exactly Filippo calculated the disposition of the bricks and the 
massive stone beams is another of the dome's mysteries. F^owever, in 
Historia Jtorentinorum, written sometime during the 1490s, the humanist poet 
and historian Bartolomeo Scala offers a hint as to how he might have done 


Brunclleschi's Dome 

it: Tor, when the centre [of the dome] was pinpointed and marked,' Scala 
clamis, Tilippo stretched a cord from the centre to the circumferences. 
Carrying on this process around in a circle, he determined in what order 
and according to what curvature the bricks and mortar were to be placed 
on the wall by the masons.' 

That is, in order to guide the laying of the bricks, Filippo ran a cord 
(what the documents call corda da murare, or 'building string*) o utw ards 
from the centre of the dome to the inside edges of the masonry. This cord, 
whrch could be swept 360 degrees around the cupola, "would have risen and 
then progressively shortened as more courses of bricks were added and the 
dome's radius shrank from yo feet at its foot to only 10 feet at the top. 
The inclination of the bricks as well as their radial positionings could 
tKerefore have been caref ully monitored. 

Scala's account is supported by Manetti, who claims that Filippo used 
this same procedure when vaulting the Ridolfi Chapel. In this experiment 
the capomaestro used a cane that was fixed at one end and 'circled upwards, 
gradually narrowing as it pressed constantly on the bricks on its unfixed 
side'. This device anticipates the modern-day 'trammel' used by bricklayers 
in order to set out circular walls. The trammel consists of a horizontal 
wooden plank that pivots on an upright metal bar fixed at the centre of the 
wall's curvature. Describing an arc as it rotates round this axis, the plank 
indicates the position in which each individual brick should be laid. 

Still, the curvature control device at Santa Maria del Fiore was 
obviously a much larger instrument: if it was to stretch from the centre of 
the dome to its circumference, the corda da murare must have been 70 feet 
long at least. This unwieldy size would have presented certain problems. 
F4ow, for example, was the cord prevented from sagging in the middle and 
therefore causing inaccurate measurements? Was a system of pulleys used? 
Or was it tautened and then smeared with wax like the ropes used by 

wooden pole would have had to have been"T^o teet nigh to reach from the 
ground to just the base of the cupola, and almost 300 feet high to reach its 

surveyors in the Middle Ages? 

But most perplexing is how the cord was fixed at the dome^s centre. A 


The Pointed Fifth 

top. The average height of a mainmast for a ship in the British Navy 
during the eighteenth century was 120 feet, and such masts could be built 
only with wood from the forests of the New World — Quebec, Maine and 
New Hampshire — since no trees of sufficient height were to be found 
anywhere in Europe. As one commentator has observed, 'One would have 
to fantasise an enormous trunk of a California sequoia hoisted onto a 
central tower or suspended platforms'.^ 

Whatever Filippo's method of controlling the curvature of the dome, it 
had its critics. Not surprisingly, the most insistent of these came from the 
camp of Lorenzo Ghiberti. Late in 1425 Lorenzo's deputy, Giovanni da 
Prato, appealed to the wardens that Filippo was failing to observe the 
terms of the 1367 model. As capomaestro, Filippo had of course sworn his 
allegiance to this sacred structure, just like all of the capomaestri before him. 
Yet Giovanni was dissatisfied. F^e voiced a number of complaints, the 
most serious of which was a claim that Filippo was not building the 
cupola according to the proper profile, the quinto acuto or 'pointed fifth' 
curvature established by Neri di Fioravanti. 

This pointed profile was important to the cupola both structurally and 
aesthetically. The pointed arch was, of course, the favoured Gothic 
method of spanning space: the arches in the nave of Santa Maria del Fiore 
are pointed, for example, as are those in the naves of most Gothic 
churches. The pointed arch has two distinct advantages over the rounded 
or semicircular one that would come to dominate architecture throughout 
the Renaissance. The first has to do with proportions, for a pointed arch 
rises higher than a semicircular one of equivalent span. In 1367 this factor 
no doubt influenced the thinking of the wardens of Santa Maria del Fiore, 
for a dome with a pointed profile was able to stand as much as a third 
higher than a semicircular one built over a tambour of equal diameter. 
Only with a pointed curvature, that is, could the cupola reach the desired 
height of 144 hraccia. 

The second advantage of a pointed arch is structural. The horizontal 
thrust of an arch or dome varies inversely with its rise, and since a pointed 
arch rises higher than a rounded one it naturally generates less thrust. In 


Brunelleschi's Dome 

fact, the architects at the Cathedral of Milan believed that pointed 
arches produced no horizontal thrust whatsoever. They were mistaken, of 
course, though a quinto acuto arch does generate as much as 50 per cent 
less radial thrust than a shallower, semicircular one. It therefore 
requires less abutment and has a lower tendency to crack or burst at its 

The quinto acuto profile demanded in 
1367 is a geometrical figure produced 
when the radius of curvature in the 
intersecting arches is four-fifths of the 
resulting span. The radius of curvature 
m a semicircular vault, by contrast, is 
only one half the diameter, leading to 
a much shallower and more rounded 
profile. It was this figure about which 
Giovanni da Prato raised the alarm. In 
a submission to the Opera del Duomo 
he maintained that the dome had been 
'falsely built* because Filippo was 
constructing it 'half round' and not as 
the specified pointed fifth. It was being 
built, that is, as a mezzo acuto, halfway between a semicircular arch and a 
pointed fifth. The result would be a dome incapable of reaching the 
required height. And Giovanni attributed this error not to some fault in 
the system of curvature control but, instead, to Filippo's ignorance. 

'I, the aforesaid Giovanni,' he wrote with some indignation, 'declare that 
it seems to me that the angle chosen and suggested decades ago ought not 
to be changed or modified by lowering it for any reason whatever.' The 
dome would be aesthetically marred otherwise, he insisted, not to mention 
structurally unsound. In short, Filippo's error in deviating from the 
established curvature would 'brazenly spoil and endanger the church'. This 
submission ends, unsurprisingly, with a bitter personal attack on Filippo: 

14. The quinto acuto arch. 


Dante reading from the Divine Comedy in front of Santa Maria del F 


A fifteenth century panorama of Florence 

A view of the belltower and cathedral 



The buttresses and ribs of the dome seen from the lantern 

The interior of the dome with Vasari s fresco 

The air space between the two shells of the dome with the 
herring-bone brickwork visible in the bottom right-hand corner 

The Pointed Fifth 

This has happened because of ignorance and presumption on the part of those to whom the 
execution has been entrusted, and who are being well paid and compensated for it. And I 
have written this so that if it befalls which all reason tells me must befall, and the 
building is spoiled and put in danger of ruin, I shall be excused and blameless. For 
God's sake, be prudent, which I am certain you will be. Think of the danger that befell 
the cathedral of Siena for trusting a dreamer incapable of reasoning. 

The tone is that of a bibUcal seer predicting future calamities should his 
words go unheeded. The unfinished extension to the cathedral of Siena to 
which he refers was a gargantuan folly that was partially torn down in 1357 
after plague struck and funds ran out — a catastrophe that had for obvious 
reasons haunted the minds of the builders of Santa Maria del Fiore. 

The motives behind Giovanni's submission to the Opera were not 
perhaps the purest, especially since there was no basis for his claims. The 
shells, as built, conform exactly to the specified quinto acuto profile, and no 
corrections appear to have been necessary at any point during the 
construction. The fact that Giovanni was so mindful of his own 
reputation ('I shall be excused and blameless'), as well as so obviously 
resentful of the fact that Filippo was 'well paid and compensated' for his 
work, leads one to suspect a motive of jealousy. 

In 1425 Giovanni had good reasons to be jealous o^ Filippo, even 
though he was himself an accomplished man, a respected humanist scholar 
who had composed a famous philosophical treatise, the Paradiso degli Alherti. 
F^owever, like Lorenzo he had thus far failed to make an impression in the 
field of architecture. Filippo's model for the wooden chain had been 
selected over one of his own, winning the capomaestro the very substantial 
prize of 100 gold flonns. In the same year Filippo also won the 
competition for the design of the castello. Meanwhile, of course, his ox- 
hoist had been a great success and the sandstone chains, the second of 
which was being laid in 1425, were working according to plan. Filippo's 
reputation, in short, had never been better. To complete his triumphs, a 
few months earlier Lorenzo Ghiberti had been suspended from his duties 
as capomaestro, possibly because of Filippo's intrigue involving the wooden 


Brunelleschi's Dome 

chain. He would be reinstated shortly afterwards, albeit with reduced 
responsibilities and powers. The Ghiberti faction had reached its lowest 

Giovanni da Prato's submission to the Opera del Duomo did not end 
with complaints about the curvature of the dome. His document returned 
to his earlier obsession with light in the cathedral, complaining that, lit 
only by the eight windows m the tambour, as well as by the oculus at the 
top, the cathedral would be made 'murky and gloomy' inside. To prove his 
point, he drew a section o{ the cathedral showing how a beam of sunlight 
entering one of the windows in the drum would be insufficient to 
illuminate either the cupola above or the crossing below. 

The illumination of a church was an important architectural considera- 
tion. Gothic builders had sought to fill their churches with plenty of light 
by designing enormous windows filled with stained glass, but the merits of 
light' or 'dark' churches were matters of considerable debate during the 
Renaissance. Alberti, for example, argued that churches should be dark 
inside, lit only by candles and lamps. But Giovanni's complaint about the 
murkiness of Santa Maria del Fiore was to be echoed over a century later 
in Rome when Michelangelo, taking over the construction of St Peter's, 
criticised the previous capomaestro, Antonio da Sangallo, for designing a 
dome that would render the cathedral so dark inside that nuns would be 
raped and criminals concealed. 

In Giovanni's view there was only one way to save Santa Maria del 
Fiore from darkness: he urged the wardens to dust off and reconsider his 
old, rejected plan in which twenty-four windows were to pierce the base of 
the cupola and thereby fill the church with glowing light. His tone became 
hectoring and apocalyptic: 'Per dio uogliate fro uederui,' he begged them ('For 
God's sake, take care of it'). Once again he sought to absolve himself of 
any responsibility should things go wrong: 'I have written this in order to 
be blameless if nothing should be done about this problem.' 

But Giovanni's pleas again fell on deaf ears. In the amendments made to 
the cupola project in January' 1426, Filippo wrote: 'We make no special 
suggestions regarding the light because the illumination from the eight 


The Pointed Fifth 

windows below seems to be adequate.' He added that if it should be 
discovered that more light was required, then windows could be 
incorporated at the top of the dome — a solution already angrily rejected 
by Giovanni as one that could only be advanced 'by a fool of small 
understanding'. It was evident that the Opera sided with Filippo rather 
than Giovanni, because construction proceeded on the cupola as before, 
with the same curvature and without windows at the base; and several 
weeks later Filippo received his salary increase to loo florins per year. 
Giovanni, meanwhile, was paid lo gold florins for his advice, after which 
he remained on the periphery of the project. 

But this debate was not the last that Filippo would hear of Giovanni da 
Prato. Soon afterwards the capomaestro began work on another invention, 
one which would enjoy far less success and esteem than any of his previous 
ones, and Giovanni would have his revenge. 


Bricks and Mortar 

DESPITE HIS SUCCESSES in the early years of the dome's 
construction, Filippo must have been dogged by the knowledge 
that once the dome reached a height o{ 30 hraccia the wardens 
would meet again to consider whether or not to continue building without 
centring. Early in 1426, after the second sandstone chain had been swung 
into place, that moment arrived. The dome had risen to 70 feet above the 
drum, and the shells, curving inwards, had passed the critical angle of 30 
degrees, above which friction alone would no longer keep the masonr\' in 
place until the mortar cured. 

In contrast to the furore when Filippo first floated his plan, in 1426 the 
debate over whether to continue building the dome without centring 
appears to have gone smoothly. The capomaestro, now at the height of his 
powers, carried the day: 'We still do not recommend centring,' the 
amended project reported, citing the difficulties of building the necessary 
scaffolding. But it remained to be seen whether this feat could successfully 
be accomplished. 

The documents of February 1426 give no more than the merest hint 
how Filippo's plan would be implemented. At the same time that it was 
decided to vault the rest of the dome without centring, another 
amendment was adopted: in certain parts of the cupola a series of uniquely 


Bricks and Mortar 

shaped bricks were to be laid in a special fishbone bond. The twelve-point 
memorandum of 1420 had decreed that after the two shells reached a 
height o{ 24 hraccia, either brick or tufa stone should replace sandstone to 
lighten the load. Brick was ultimately chosen because tufa was not readily 
available m the vicinity of Florence and so needed to be imported. The 
Opera therefore contracted for hundreds of thousands o{ bricks, and 
Filippo began designing special wooden moulds in order to shape them. 

The size of bricks was carefully regulated in Florence. The basic brick 
used in the construction industry, the mattone, was about 10 inches long and 
5 inches wide. All brickyards were required to display the mould for this 
brick, stamped with an official seal, where it could be consulted both by 
their customers and by inspectors from the Masons Guild, who would 
arrive on the premises wearing distinctive blue capes and silver badges. 

The cupola, however, called for bricks of more unorthodox designs: 
rectangular bricks, triangular bricks, dove-tailed bricks, bricks with flanges, 
bricks specially shaped to fit the angles of the octagon. The sizes of these 
bricks were so various, and the templates used to design them so 
numerous, that at one point parchment ran short and Filippo was forced 
to improvise: he resorted to palimpsests, drawing his designs on pages torn 
from old books specially bought for the purpose. 

These templates were sent to a barrel-maker who constructed the 
wooden moulds used to shape the bricks. Once the mould was finished, it 
went to the brickyard. These were normally located in the countryside, not 
only in order to spare Florence the twin nuisances of fire and pollution, 
but also to be close to the clay pits as well as the supplies of the timber 
and brushwood that fuelled the kilns. Dug from the pits, the clay was 
kneaded into a smooth and even consistency bv the exertions of barefoot 
men, who trod it underfoot like grapes. The resulting 'pug' was then 
moulded, seasoned and, finally, baked. The firing would last for several 
days, but because the kiln was heated to a temperature of 1,000 degrees 
Celsius the brickmaker had to wait almost two weeks for it to cool down 
enough for the bricks to be unloaded. The average kiln held as many as 
20,000 bricks and, fired every three weeks, could bake over ^00,000 a year. 


Brunelleschi's Dome 

Even at this rate, however, it would have taken one kiln over thirteen years 
to produce enough bricks for the dome. 

Manetti claims that Filippo himself inspected each and every brick 
destined for the dome. This is surely an exaggeration given that as many as 
four million were used. But quality control was obviously a major concern 
for the capomaestro. Bricks often shrank or cracked during firing because the 
clay had not been properly seasoned, and shipments were rejected if the 
consignment was not of the quality required. Ideally the clay was dug in 
the autumn and, after being moulded, was buried in sand in order to avoid 
frost damage in the winter. In summer the unbaked bricks were excavated 
and then reburied in beds of moist straw to prevent them from cracking in 
the heat. Alberti cautions that a brick must be seasoned for two years 
before being burned, making for a process as time-consuming as treating 
timber. Nor was the baking of bricks the cleanest of occupations: a joke in 
Florence claimed that only kilnmen washed their hands before visiting the 

Equally important to the building of the dome was the quality of the 

mortar, in which Manetti claims Filippo also took a personal interest. 

Throughout the Middle Ages mortar was made from mixing sand and 

water with quicklime (calcium oxide), a substance obtained by heating 

limestone in a kiln. Making mortar for a structure the size of the dome 

called for enormous quantities of limestone. Most brickmakers burned 

O ^ limestone as well as bricks in their kilns, using a separate furnace for the 

"Zt * iC operation, which took some three or four days. Lime-burning was a 

^ ^ noxious process that prejudiced the health of anyone living downwind. It 

was dangerous for another reason as well, since air pockets in the 

limestone could cause explosions in the kiln. Air pockets were often the 

^ ^^ result of fossils, a phenomenon with which stone-cutters, for obvious 

-p 6 reasons, had become more familiar than anyone else. These petrified 

— ^ ^ remains were objects of great curiosity: Alberti, in some fascination, 

£ describes having seen worms with hairy backs and a great number of feet 

-^ >^ living' inside blocks of limestone. 

^ ^ As we have already seen, the speed with which a mortar set determined 




Bricks and Mortar 

the techniques of construction. Medieval mortar set in two phases. The 
first took place after a few hours, when the material was no longer plastic, 
while the second was not complete for a much longer period. This second 
setting required carbon dioxide absorbed from the atmosphere to convert 
the calcium hydroxide of the mortar paste back into calcium carbonate, 
the basic constituent of limestone. This is the same chemical reaction that, 
with greater leisure, creates stalactites on the roof of a limestone cavern, 
where carbon dioxide turns the calcareous matter in the dripping water 
back into its native limestone. 

Alberti claims it is possible to tell when this second set occurs because 
the mortar puts forth 'a kind of moss or little flower well known to 
masons'. It is not easy to know which plant he is referring to, though the 
most likely candidates are mosses from the Bryum, Tortula or Grimmia 
families, all of which grow on limestone walls several months after a 
mortar is applied. It has been speculated that Filippo may have sped up the 
process by using a quick-drying mortar, possibly even pozzolana, which 
would have been a truly remarkable innovation, marking the first use of 
Roman cement for a millennium. But mineralogical tests conducted m the 
1970s revealed no material difference between the mortar in the cupola and 
that elsewhere in the cathedral. In each case, however, sodium carbonate, 
or soda ash, was present, a mineral used in glass-making. It would have 
led, whether intentionally or not, to a fairly rapid stiffening of the mortar. 

Mortar was always mixed on the site. The process took about a day 
since if the quicklime was not well slaked — that is, thoroughly mixed with 
water — it would damage the brickwork. The mixing was done on the 
cupola itself because it needed to be applied while still plastic. Lime, sand 
and water were all hoisted to the top of the dome, where the lime was 
slaked and then combined with the sand. Slaking generated great heat and 
caused the quicklime to expand and then disintegrate into a powder. One 
of the perils involved in mixing the mortar was burning one's hands on the 
quicklime, a corrosive substance otherwise used to hasten the decomposi- 
tion of corpses and so lessen the stench and danger of disease in 


BruncUcschi's Dome 

chiirclivards. k was also cmplo\cd b\- ranners ro scorch the hair oft animal 

Once properly mixed, the morrar \n as poured b\- the masons on to their 
mort^ir boards and, in time-honoured fashion, spread over the brickwork 
\N4th rroNN'els. Each ot the eicjht teams ot masons laid its bricks on the 
inside ot the wall and worked ourvwirds, with the bed joints ot successive 
courses inclining ^is the structure rose. Both shells were raised simultane- 
ously, with the inner built to a thickness ot o teet, a width ot over ten 
bncks. Tlie outer shell, much thinner, \ a third that size. 

\\ ork advanced at a slow pace because the ei^ht teams ot masons \\ ere 
torced to w ait until each ring gained strencjth betore they bovj,m a new one. 
Tlie average rate ot construction has been estimated at less one course 
per w cek. meanincj the cupola would have risen at a rate ot rouc^hlv a toot 
each month. Erecting the dome with a centrincj would have demanded a 
much more rapid construction because ot the tendency ot the wood to 
detorm or 'creep' over rime. But a srrucuire the size ot the aipola could 
nor possibly have been built swiftly enoucjh to avoid this detormation — 
\et .mother reason tor vaulnnij without centnncj. 

TTie adhesion ot the bricks was not FilippK>'s only worn at this p^omt. 
These were dangerous times tor ihc rc.ims ot masons, who now had to 
work on w\ills that leant inw\irds at xn al^irmiiiij an^le. A dome built with a 
w ooden centring had a comtorting nervvork ot scat^oldinc to break a tall 
and obscure the \iew ot the ab^'ss. In this case, however, there was nothing, 
the masons simplv moved around the p>erimeter ot the cupola on pcrui 
(narrow platforms made from willow withes and supp>orted on wooden 
rods inserted into the masonry^ while below them ^'awned the chasm. In 
order to pacit\" the nenous masons, Filippo built a parapettc, or balcony, on 
the inside ot the vault- This contraption consisted of a senes ot boards 
erected on han^^ scaiiolds projecting trom the masonrv. A plattorm 
much wider than the pcntu it sened both as a s,itetA" net and — even more 
Mtal — as a screen. .Accordin^j to the documents, it w as intended "to prevent 
the masters from lookincj down*. 

Other saterv" measures were also implemented. Masons working high on 


Bricks niid Mori.u 

llu' u.ills wcvc oi\c\) Ic.nhcv s.ilcu li.uncsscs. .iiul lluii- wine was (o l)c 
diliilcd Willi .1 thud p. Ill of vv.ilci. A iiiiMiMv nonn.iIK irsnvc'd (or 
prci^ wdiiumi. Aiu'oiic viol. u mo ilus Liiii'i rule was subject to a fine of 
lo Inc. ov ilu- ci]iii\.\lciii of clcNcn days' work. Workers were also 
forbidden to ir.nisport their tools, lunches or. worse still, themselves m the 
tubs ol the hoist. Nor were they permitted to swing inside the hoisting 
rubs in order to c.ipturc pigeons nesting in the cupola. Nesting pigeons 
were a nuisance to m.isons. 1 )urmg the construction of 
Westminster Abbe\', canvas sheeting had to be uset] to keep them from 
l.iking u[^ residence among the stones .ind be.ims of the- h.ilf-finisheci 
structure. 1 he pigeons so daringU" ca^Muieti b\ the masons .it S.iiita Maria 
del liore before the eiiict took effect were pro[).ibl\ tiestined for the dinner 
pot. Bl.ickbirds .ilso met this f.ite. for .i rare luxury for workmen, 
bcin^^ e.iteii for the nu)st p.iii oiil\- on Suiidaw 

I liese x'.irious s,ifcM\ iiuMsures to have worked: .ifter the two 
de.ilhs in the south tribune in the summer of 1420, onl\' one other f.italitv 
IS recoicied. of .1 m.isoii ii.imed Nenno cli (.hello who fell to his death 
in 1\' 1422. It is .111 .ilmost mir.iculous s.ifetv record consicienng the 
number of men emplo\ed, the perilous nature of their work and the many 
years the project took to complete. 

Another ha/.ird faced bv the m.isons uiieniplo\nient. As the shells 
rose .Hid the circumference gradu.illv narroweci, fewer bricks needed to be 
laid .ind iheiefore fewer masons were needed. I wentv-five of them were 
sacked in /\pril 1426. though 111 this case the redundancies may have 
resulted fn)m .1 l.ibour dispute. Manetti claims the m.ister masons 'selfishly 
unionised themselves' — an .ict contrary lo ilorentiiu^ l.iw — .ind went on 
strike for higher pAv. Conflict over working conditions ma\' also have 
played a part in the strike. Such strikes were not unknown m llorence, 
where the .ill-powerful guikis were to extend liberties to the 
workers upon whose toils their own prosperity ciepended. 1 he pre\'ious 
ccntur\ seen strikes, secret meetings, rock-throwmg crowds, the 
beginnings of working men's associations, even full-scale insurrections.' 
The most f.imous example of the l.itter was the so-called Caompi uprising 


Brunelleschi's Dome 

of 1378, when the city's downtrodden cloth-workers revolted against their 
masters and, amid mass disturbances, set fire to the palaces of the 
aristocratic families and temporarily seized control of the Republic. 

No such revolution was permitted to erupt at Santa Maria del Fiore. 
Filippo responded in ruthless fashion, promptly sacking the masons and 
hiring Lombards to replace them — the strike-breaking technique beloved 
of later opponents of trade unions. Finding themselves unemployed, the 
dismissed masons humbly petitioned Filippo for the return of their old 
jobs. Vasari, who also tells the story, gleefully reports that Filippo did 
indeed rehire them, but on lower salaries, 'so instead of getting something 
more, as they thought they would, they suffered a loss, and in venting their 







y '^) 

d and di 

urea an 



d themsel 

It IS safe to assume that the masons, like the stone-cutters and 
ironmongers, were initially puzzled by what the capomaestro required of 

them. It comes as no sur- 
prise that the brickwork in 
the shells was as complex 
and inventive as everything 
else Filippo designed for 
the cupola. The bricks were 
not merely laid in horizon- 
tal layers: at regular inter- 
vals in both shells the rings 
were interrupted by larger 
bricks laid on their ends — 
that is, at right angles to 
the horizontal courses. 
This angled brickwork is 
the spinapescie (fishbone) 
bond mentioned in the 
1426 amendment. These vertical bricks, each of which passed through four 
or five horizontal rings, ascended in diagonal bands to the top of the 

V/»j ^^'^.i. «■■"•" .?JJ-" 

[5. Herring-bone brickwork. 


Bricks and Mortar 

dome, forming a zigzag or herring-bone pattern. Filippo must have known 
that these spirallmg bands of upright bricks would constitute planes of 
weakness, since they were less able than a more conventional 
bond to counter the hoop stresses that threatened to crack the dome. 
Why, then, should he have chosen to use the herring-bone bond? 

The reason behind Filippo's choice of this pattern lies in the particular 
structural behaviour of arches and domes. A dome is built on the principle 
of an arch, whose stones, as we have seen, are kept in place by mutual 
pressures brought into play by their own weight. Once complete, each of 
them is under circumferential compression and therefore, like an arch, 
becomes self-supporting. But the problem m constructing a dome arises 
from the fact that these rings cannot be built instantaneously. Some form 
of temporary support is therefore needed until the rings are complete 
because, until they are closed, the tendency of the masonr\' is obviously to 
fall inwards. 

Filippo used the herring-bone bricks in order to counter this tendency. 
The upright bricks projecting from the horizontal courses served as what 
one of the cathedral's capomaestri, Giovanni Battista Nelli, surveying the 
cupola over two hundred years later, called morse, or 'clamps'. From his 
observations Nelli realised that Filippo had adopted a different pattern of 
brickwork at the level of the second sandstone chain, as the masonry began 
curving inwards, and that this pattern had helped to hold m place the 
surrounding horizontal bricks as the mortar cured. Every three feet or so, 
these upright bricks interrupt the horizontal courses, subdividing each new 
layer into shorter sections roughly five bricks long. While under 
construction, the short sections were connected by the upright bricks to 
several completed layers beneath. Each row of five bricks, that is, was 
locked into position by the vertical bricks on either side. These acted 
rather like book-ends, keying the new layer to the completed, self- 
sustaining ones beneath. 

The incomplete courses of bricks were therefore held m place not by an 
internal support (as m the case of a wooden centring) but by a pressure 


Brunelleschi's Dome 

applied from either side. Even before the ring was complete and the 
mortar had cured, the short sections oi bricks were transformed into self- 
contained horizontal arches capable of withstandmg the inward pull of 
gravity. The herring-bone pattern is therefore essential to the dome's 
structure, an mgenious system used by Filippo as part of his technique to 
do away with the need for an elaborate centring. In On Architecture Alberti 
later describes this technique as being essential for building a vault without 
centring, because connections bind the weaker components to the stronger 
ones. He compares the result to the human body, in which Nature 'joins 
bone with bones and binds the flesh with tendons, introducing 
connections in all directions in length, breadth, depth and slantwise'. 

Where exactly Filippo learned of the herring-bone bond is one of the 
dome's unsolved mysteries. The pattern had of course been known to 
masons and bricklayers for many centuries. The Romans made extensive 
use of the bond they called opus spicatum, and the pattern is also found in 
the half-timbered brick walls of Tudor houses in England. In both these 
cases, however, it is decorative rather than structural; indeed, the Romans 
used it only in ornamental paving on the floors of their villas. 

Slightly further afield, systems of interlocking brickwork similar to that 
in the cupola in Florence can be found in certain Persian and Byzantine 
domes, leading some scholars to speculate that Filippo may have visited 
these lands. This hypothesis is not improbable given the trade link with 
Asia Minor (which was so well known to Italians as early as the thirteenth 
century that Marco Polo did not consider it worth describing) as well as 
Filippo's many 'lost years' between 1401 and 1418. He may also have gained 
second-hand knowledge of these domes from merchants returning from 
the East or even, possibly, from the many Muslim slaves in Florence. No 
wealthy family in Florence could do without at least a couple of these 
'domestic enemies' (as Petrarch called them), among whom were found 
Turks, Parthians and Chaldeans, all from the Near East. Still, the 
majority of these slaves were adolescent girls, and their familiarity with 
Seljuk vaulting techniques must have been scanty. 

Having inspected the dome's brickwork, Nelli was confident that the 


Bricks and Mortar 

method could be applied elsewhere, daring to envision other such 
enormous structures. 'Operating in this manner/ he wrote, 'any massive 
curved structure can be raised from the ground to any height whatsoever 
without support from centring or scaffolding.' The dome of another of 
Filippo's designs, Santo Spirito, was built in this way, and Antonio da 
Sangallo the Younger made use of it m the next century. But the full 
magnitude of Nelli's claim has never been tested except at Santa Maria del 
Fiore. This is for the simple reason that no masonry dome larger than 
Filippo's great cupola has ever been constructed. 


Circle by Circle 

THE BOOK OF GENESIS tells us that after the Flood, when 
everyone on earth still spoke the same language, some of the 
descendants o{ Noah travelled east into the deserts of Babylonia, 
in modern-day Iraq. Hoping to make a name for themselves, these new 
inhabitants o{ Babylonia took it upon themselves to found a great city 
named Babel, or 'the gate of God': And they said, Go to, let us build us a city, and 
a tower, whose top may reach unto heaven. 

The rest of the story is well known, of course. It is a parable of the 
ambitious pride of mankind and, more specifically, of architects. Using 
kiln-baked bricks mortared together with tar, the people of Babel built an 
edifice that rose to an incredible height. But the tower was never finished. 
Angered by man's attempt to reach the heavens — to build beyond his 
assigned station on earth — the Lord confounded the tongues of the 
builders so that no one could understand anyone else's speech. Not 
surprisingly, the ambitious project ended prematurely and unhappily. 

Modern commentators speculate that the story of the tower of Babel is 
an attempt by the ancient Hebrews to account for the enormous, half- 
ruined ziggurats, or stepped pyramids, that had been raised by the 
Sumerians, the world's oldest civilisation. The story also seeks to account 
for linguistic diversity, for we learn that after abandoning their tower, the 


Circle by Circle 

Babelites with their myriad new languages were dispersed across the face of 
the earth, giving rise to new nations, each with its separate tongue. But the 
story is likewise an architectural version of the Fall of Man. The attempt 
to reach the heavens, and therefore to rival God, recalls Adam and Eve's 
ambition to gain forbidden knowledge in the Garden of Eden. The great O 
tower — a would-be bridge between man and God — becomes an ^^ 
architectural equivalent of the Tree of Life, which likewise would have "^ 
erased the difference between the Creator and his creatures. ^i2 

Bu ildings of large dimensions have always ppsed mora l jyrohlpms.^ A ^ 
number of Roman authors disapproved of excessively large edifices either 
because of their lack of utility or because of the tremendous expenditure 
involved in their construction. Plutarch, for example, condemned the ^ 
enormous baths and palaces of the Emperor Domitian, and both Pliny and K ^ 
Frontinus vehemently rejected the Seven Wonders of the World, which 
the former regarded distastefully as a foolish display of wealth on the part ^ -, 
of kings. By contrast, the aqueducts maintained by Frontinus, though V * 
immense, served the important purpose of bringing fresh water to the 
citizens of Rome. 

In the twelfth century, the Cistercian abbot Bernard of Clairvaux 
condemned the vast height of the new Gothic churches that were rising 
everywhere across France. Such suspicions can also be found in the 
writings of Leon Battista Alberti, who attacks the pyramids in the same 
critical vein as Pliny and Frontinus, claiming that the 'monstrous' works of 
the Egyptians were an 'insane idea'. In light of this pronouncement, his 
positive estimation of the dome of Santa Maria del Fiore (one of whose 
virtues, he claims, is its sheer scale) comes quite unexpectedly: 

What man, however hard of heart or jealous, would not praise Pippo the architect when 
he sees here such an enornwus construction towering above the heavens, vast enough to 
cover the entire Tuscan population with its shadow, and done without the aid of beams 
or elaborate wooden supports? 

The reference to the dome's all-encompassing shadow may be an 


Brunelleschi's Dome 

allusion to the pyramids of Egypt, which were said to cast shadows as long 
as a journey of several days." Alberti justifies the gigantic dimensions of the 
dome because they reveal both evidence of man's God-given power to 
invent and the superiority of Florentine commerce and culture. Filippo 
and his masons even appear to have succeeded where the architects of 
Babel failed, for the dome towers above the heavens, achieving and even 
surpassing the aspirations o{ the ill-fated Babelites. 

Alberti wrote this famous description of the cupola soon after setting 
eyes on the half-built structure for the first time in 1428, following his 
return to Florence from exile. The wealthy Alberti clan had been banished 
from the city seventeen years earlier, when Leon Battista was only four, 
and he had subsequently been raised m Padua and Bologna. Later famous 
for his books on painting and architecture, in 1428 he was known for 
spectacular feats o{ physical prowess such as piercing an iron breastplate 
with an arrow and leaping over the shoulders o{ ten men in succession. 
Among numerous other accomplishments he was a horse-tamer and the 
author of treatises on both the arts of navigation and the manners of his 
pet dog. He invented a disk to compose ciphers (a sort of prototype of the 
Enigma machine) as well as an astrolabe to survey the ruins of Rome. No 
subject seemed to escape his attention: Greek, Latin, law, mathematics, 
geometry. But he took a special interest in architecture, particularly in 
Filippo's dome, over the top of which, according to legend, he was able to 
throw an apple. 

For Alberti as for everyone else in Florence, watching the dome rise 
above the city was the most enduring and breathtaking spectacle of the 
age. Alberti was probably the most interested and informed of these 
observers, acting as a reliable eyewitness to what later writers have doubted, 
namely that the cupola was raised without a wooden centring. And he 
makes an intriguing observation about this engineering feat, which he says 
'people did not believe possible'. A polygonal dome can be constructed 
without a wooden support network, he claims, only if *a true circular one 
is contained within the thickness'. 

A century after its construction, the Florentine poet Giovanni Battista 


Circle by Circle 

i6. A detail from Biagio d' Antonio's Archangels in a Tuscan Landscape shows 
the dome in the background still under construction. 

Strozzi described the dome o{ Santa Maria del Fiore as having been built 
di mvinpiro, 'circle by circle'. This expression no doubt alludes to the 
technique of bricklaying at Santa Maria del Fiore: the process of waiting 
for the mortar of one course of masonry to dry before laying another. But 
even allowing for metaphor and poetic licence, it is still a slightly odd 
description if we consider that the dome is octagonal and not circular, a 
fact apparent to anyone who sees it. The difficulty in raising the dome lay 
in the fact that it was not circular. So what does Alberti mean when he 
speaks of a circular dome contained within the thickness of the polygonal 
one, or Strozzi when he says that the dome was built 'circle by circle'? 
The herring-bone brickwork, ingenious as it was, would not alone have 
been enough to stop the dome collapsing inwards. Filippo's real stroke of 
genius was in creating a kind of circular skeleton over which the external 
octagonal structure of the dome took shape. That is, the dome was 
constructed so that it contained within the thicknesses of its two shells a 


Brunclleschi's Dome 

series of continuous circular rings. The inner shell of the cupola, as we 
have seen, is the thicker oi the two, measuring between 7 feet at its widest 
and 5 feet at its narrowest. With these dimensions it was large enough to 
incorporate into its centre a complete circular vault roughly 2/2 feet thick. 
Rowland Mainstone, the English structural engineer who determined this 
form following a survey in the mid-1970s, explains that the inner dome was 
constructed *as if it were a circular dome . . . but with parts cut away from 
both the inside and outside to leave the octagonal cloister-vault form'.'^ 
The herring-bone bond was then used to secure the bricks that protruded 
forward of this circular ring — that is, those bricks on the inner shell that 
were not part of the horizontal ring. 

The outer shell posed a somewhat different dilemma. With a width of 
slightly more than 2 feet at its base narrowing to just over a foot at the 
summit, it would not be possible to incorporate a circular vault within its 
thickness. How then could it, like the internal shell, be made self- 
supporting? The problem was a lesser one, in some respects, given that it 
might have been possible to support the masonry of the outer shell on the 
back of the inner one by using a small network of centring between the 
two. But this was not the solution adopted by Filippo. 

A clue to the method used to build the outer shell in its upper levels can 
be found in the amendments made to the cupola project in 1426. As well 
as referring to the herring-bone bond, these make reference to another 
brickwork construction, a horizontal arch that would be built on the 
inside of the dome's outer shell: 'Let bricks be built in the form of an arch 
for the perfection of the circle encompassing the outer shell, in order that 
this projecting arch may be complete and unbroken.' The purpose of this 
arch, the amendment states, was to make it possible 'to bring the dome to 
completion with greater safety'. 

Once built, this horizontal arch must have served its purpose, for in the 
end the masons built eight more of them, all continuous rings that form 
part of the octagonal structure of the outer shell. They were observed by 
the cupola's first surveyor, Giovanni Battista Nelli, though their full 
importance was not recognised until Mainstone's much later survey. Each 


Circle by Circle 

one is roughly 3 feet wide and 2 feet high, and they encircle the dome at 8- 
foot intervals, the first one being found just above the second sandstone 
chain. Visible in places from the internal walkways, they project at right 
angles from the inside of the outer shell, connecting the corner spurs to 
the intermediate ribs. Unlike the stone-and-iron chains, they are not 
intended to neutralise the lateral thrust, although it is possible that they 
transfer weight from the outer shell to the inner one. They were a 
temporary measure, and if they appeared crude or obstructive they were to 
be dismantled and removed once the dome was finished. 

These nine rings served a vital function in building the cupola. They 
begin at the height — some 36 hraccia above the drum — above which the 
shell, curving inwards, had passed beyond the critical angle of 30 degrees. 
This fact explains why the arch-rings (like the herring-bone courses, which 
serve a similar purpose) were begun at this level and not at a lower one, 
where the hoop tension is much greater. They are disposed round the 
circumference o^ the shell so that they thicken it at the corners which 
would otherwise have interrupted what the 1426 amendment calls 'the 
circle encompassing the outer shell', ensuring that this circle is 'complete 
and unbroken'. The masonry of the outer shell was thus rendered self- 
sufficient during the course of its construction and prevented from falling 
inwards. Yet the rings are almost wholly disguised, being visible only in a 
few places between the two shells. From the outside the dome looks 
perfectly octagonal, as demanded by the 1367 model. Once again Filippo, 
the master of illusion, had exploited the difference between surface 
appearances and internal reality. 

Giovanni Battista Strozzi's description o^ the dome having been built 
'circle by circle' is not only a reference to the method of bricklaying or the 
series of ascending circles that compose the two shells. It is also an allusion 
to the Divine Comedy, where Dante uses this exact same phrase — di giro in 
giro —"to" describe Paradise, which is envisioned as a series oi nine 
concentric circles. The comparison of the dome to Dante's Paradise is an 
apt one for a number" oTlreasons. Filippo was a scholar of Dante, having 


ly. The nine horizontal circles within the dome's outer shell. 

dary ribs 

secondary ribs 

primar}' ri 

outer slull 


i8. A close-up of how the arch rings fit within two sides of the octagon. 

Circle by Circle 



19. Dante's circles of Hell. 

made an extensive study of the Divine Comedy in which his architectural 
instincts compelled him to calculate geometrically the precise dimensions 
of Paradise; and domes have always been a conventional symbol of heaven. 
In both Eastern and Western art the ceilings of the most revered shelters 
have been associated with the heavens, visions of which have therefore 
often been executed on their surfaces in paintings or mosaics. Persian 
domes were said to express the flight of the soul from man to God. 

But the nine arch-rings built by Filippo in the outer shell of his dome 
recall nine other famous rings: those of Dante's Hell, which is composed 
of nine rings that descend conically into the earth, rather like an inverted 
dome. This too is an apt comparison, for in 1428, shortly after the first of 
the arch-rings was completed, Filippo was to begin his own infernal 


The Monster of the Arno 

BY THE SPRING of 1428 work on the cupola appeared to be 
progressing smoothly. The dome had risen more than 70 feet above 
the drum in less than eight years, and with the diameter now 
narrowing it could be expected to ascend even more swiftly in the years to 
follow. But 1428 would be the year of Filippo's first real setback smce 
work on the dome had begun. His undoing was brought about by what 
must have seemed a minor problem in comparison with the ones he had 
already solved. 

Over a hundred years earlier it had been decided that every inch of the 
exterior surface of Santa Maria del Fiore, with the exception of those parts 
tiled in brick, should be covered with marble. Marble was the typical 
building material of Antiquity, but it had been used only sparingly in 
Florence, which was built, as we have seen, primarily from sandstone. 
Other than for his work on the cupola, Filippo would use no marble at all 
on his other buildings. Unlike sandstone, marble was scarce in the vicinity 
of Florence, and transporting it from afar without damaging it was 
difficult and onerous. Undaunted by these difficulties, the planners of 
Santa Maria del Fiore had ordered that three colours should encrust the 
cathedral: the greenish black stone known as verde di Prato; the red stone 
marmum rubeum; and, finally, a brittle white marble called hianchi marmi. This 


The Monster of the Arno 

last stone would cover the eight enormous brick ribs of the cupola, and in 
June 1425 the Opera del Duomo signed a contract for 560 tons of it. 

Bianchi marmi was supplied from quarries near Carrara, 65 miles to the 
northwest of Florence. The marble from this remote district possesses a 
long and illustrious history. It was first exploited by the Romans, who 
used it for the Apollo Belvedere (which would be excavated at Frascati in 
1455) and in the Arch of Constantine. Later Michelangelo would carve 
some of his most famous statues from it, including his David and the Pietd. 
In fact, Michelangelo spent a good many months of his life in the steep, 
dazzlingly white mountains around Carrara, reopening and inspecting old 
Roman quarries and fantasising about carving gargantuan shapes into the 

Carrara marble was justifiably the most sought-after in Europe: hard, 
clean-breaking and a chaste white, it was perfect for carving and 
ornamentation. It was also extremely expensive. Nevertheless, the Opera 
had been bringing this white marble to Florence for more than a hundred 
years, using it, for example, to clad Giotto's campanile. In this enterprise 
the citizens of the Republic had been conscripted into service: in 1319 the 
Opera decreed that the people were to lend a helping hand whenever 
marble for the cathedral was shipped along the Arno. It was to be 
transported by those who operated small craft, primarily fishermen and the 
renaiuoli, men who scratched a meagre living by harvesting gravel for the 
building trade from the Arno's numerous sandbanks. This seems to have 
been an attempt on the part of the Opera to legislate for a sort of 'Cult of 
the Carts' such as that seen during the twelfth century in France, where the 
population, gripped by a pious hysteria, helped to drag carts of stone from 
the quarries to the cathedrals. 

The acquisition and working of marble from Carrara was a complex, 
delicate and occasionally dangerous business. Extraction methods were 
similar to those for the sandstone at the Trassinaia quarry. Blocks of 
marble were first of aU cut from their mountain beds by roughmasons 
wielding an array of tools: picks, hammers, crowbars, wedges, even heavy 
pole-axes to break the larger pieces. Besides brawn, the roughmason 


Brunelleschi's Dome 

required a precise knowledge of the seams and an ability to cut both with 
and against the grain. After it was rough-hewn into shape, a more skilled 
artisan cut the stone to the exact size and shape specified by the templates. 
An even more varied assortment of tools, all of tempered iron, was used in 
carving the white marble, a stone notoriously difficult to work. A fine- 
pointed implement called the suhbia chiselled the block to within an inch or 
two of the penultima pelle, or the second last skin. Then a chisel with a notch 
in the centre of the blade, the scarpella, was used, followed by the lima raspa, 
or roughing file, which came in a variety of shapes and thicknesses. 

After these tools had shaped the block into its proper geometrical 
profile, the surface of the stone was given three or four separate polishes. 
The first polish involved using an iron plate to rub a sharp sand across the 
stone, thus removing the irregularities of the surface. The second used a 
finer sand, or sometimes dust from a whetstone, and the third used rotten- 
stone, an abrasive red limestone powder known as tripoli. The final polish 
was performed with a putty made from tin oxide. So burnished, the marble 
would be as smooth as glass. 

Dressing the marble at the quarry had the advantage of lower transport 
costs, for only the finished stone was shipped to Florence, not the heavier 
and more ungainly rough-hewn blocks. Yet moving the stone intact over 
long distances and across rough terrains was by no means an easy process. 
If they passed inspection, the blocks were raised from the quarry with 
hoisting tackle and conveyed down winding roads on carts — two delicate 
operations — until they reached the busy town of Carrara, whose cathedral 
and principal buildings all were built from gleaming hianchi marmi. After 
export taxes were paid, they were carted several more miles to the old 
Roman port of Luni, on the malaria-ridden coast. Here they were moved 
across the beach on wooden rollers, lifted on to barges by means of a 
treadwheel crane, then launched into the waters of the Ligurian Sea. This 
leg of the journey was particularly perilous, as was discovered in 1421 when 
one of these barges sank during a storm with a loss of its cargo, a load of 
hianchi marmi destined for the cornice on the dome's rain gutter. After a 25- 


The Monster of the Arno 

mile sea voyage, the boat would reach the mouth of the Arno, up which 
the cargo was transported over sandbars and shoals towards Florence. 

The Opera was able to defray the expense of bringing marble from 
Carrara by offering some of it for sale as tombstones to the wealthier 
citizens of Florence. But at times marble tombstones originally destined to 
glorify deceased magistrates and wool merchants became part of the 
cupola instead. In July 1426, there was a shortage of good marble due to 
the high transport costs, causmg the Opera to order the cutting up of 
tombstones — presumably those from a stockpile rather than ones already 
marking graves. But by that time it was clear that a cheaper and more 
expedient method of acquiring this precious stone was needed. And 
Filippo, ambitious and inventive as ever, had just the plan up his sleeve. 

Water transport was considerably cheaper than overland carriage, which 
was prey to the vagaries of the terrain and the weather, the moods and 
endurance of the beasts of burden, and the frailty of the wagons. It was, 
for example, twelve times more expensive to transport grain by land to 
Florence than along the Arno. But water transport to Florence was made 
difficult by the Arno's capricious flow, the volume and rate of which was 
highly variable, depending on the season and the weather. The fifty-mile 
stretch from Florence to Pisa was badly silted and, in the hot summer 
months, little more than a trickle. Unlike, say, the River Thames, the Arno 
had virtually no tide on which a vessel might ride. Galleys rowing to and 
from Pisa were sometimes forced to winch themselves forward with the 
help of trees along the river bank. In periods of heavy rain the Arno was 
even more impossible. During the piena, the spring flood, it became a 
frenzied torrent. Water hurtled down from the slopes of the Apennines, 
eroding its banks, smashing bridges and inundating both Florence and Pisa 
with monotonous regularity. Even under ideal conditions, flat-keeled 
barges could travel upriver only as far as the port of Signa, stiU ten miles 
from the gates of Florence, because of the shallow water and numerous 
sand banks. As a result, all cargo bound for Florence had to be transferred 
to mules or carts and padded with straw-filled sacks for the final stretch. 

Various attempts were made to solve the problem of the Arno's fickle 


Brunelleschi's Dome 

currents. Silt was scraped from its bed by dredgers — barges rigged with 
treadmills powering buckets or scoops fixed at the end of long shafts. But 
with each flood the silt returned. River banks pulverised by floodwaters 
were shored up with the wrecks of old galleys, but these were always liable 
to drift away again. In 1444, in one o£ his last acts as a civil engineer, 
Filippo would fortify the bank of the Arno near the Porto San Marco in 
Pisa. Decades later, and most ambitious of all, Leonardo da V^inci planned 
to bypass the clogged artery of the Arno altogether by constructing a 50- 
foot-wide canal that would leave the Arno near Florence and run through 
Prato and Pistoia, 25 miles to the northeast, before swinging south and 
rejoining the river at Vicopisano, a few miles upstream from Pisa. This 
venture, like most of Leonardo's plans, was never carried out. 

But in 1426 Filippo had in mind a different solution to the problem of 
river transport. An innovator in countless other areas, he had also received, 
in 1421, the world's first ever patent for invention.^ Describing the 
capomaestro as *a man of the most perspicacious intellect, industry and 
invention', this document granted him a patent of monopoly for 'some 
machine or kind of ship, by means of which he thinks he can easily, at any 
time, bring in any merchandise and load on the river Arno and on any 
other river or water, for less money than usual'.' Until this point no patent 
system existed to prevent an inventor's designs from being stolen and 
copied by others. This is the reason why ciphers were so widely used by 
scientists and also why Filippo was so reluctant to share the secrets of his 
inventions with others. Filippo complained about this plagiarism to his 
friend Mariano Taccola in a bitter diatribe against the ignorant multitude: 

I A^ 


Many are ready, when listening to the itiventor, to belittle and deny his achievements, so 
that he will no longer be heard in honourable places. But after some months or a year 
they use the inventor's words, in speech or writing or design. They boldly call themselves 
the inventors of the things that they first condemned, and attribute the glory of another to 

The patent for invention was designed to remedy this situation. 


The Monster of the Arno 

Possibly Fihppo already had in mind a cheaper and more effective means 
of shipping marble up the Arno; but the patent makes clear that the 
invention would have a wide application, being of great benefit *to 
merchants and others'. Once built, this curious-looking vessel quickly 
became known as // Badalone, or 'the Monster'. According to the terms of 
the patent, any boat copying its design, and thereby violating Filippo's 
monopoly, would be condemned to flames. 

Not much is known about the precise design of // Badalone, the finer 
points of whose construction Filippo, despite the protection of his patent, 
kept secret for fear of imitators. Manetti and Vasari do not even mention 
the episode, which does not exactly redound to their hero's glory. 
However, it must have been technologically novel and adventurous in 
order to be deemed worthy of a patent. The nickname implies a great and 
perhaps even ungainly size, which would have been one of the boat's chief 
economic advantages — and possibly also the source of its undoing. 

The only picture we have of the boat was done by Mariano Taccola, to 
whom the capomaestro, in a rare fit of candour, appears to have described its 
construction. In his book De ingeneis Taccola shows how a wagon with 
fourteen wheels that transports the marble overland from the quarry can 
be converted into a raft tugged by a rowing-boat. We know that in 1427 
Filippo borrowed from the Opera a rope with which to tow II Badalone, It 
is therefore very likely that the boat consisted of a large, raft-like wooden 
platform possibly buoyed by a number of floats, such as barrels, and 
tugged along the river either by another boat or by oxen toiling up the 
towpath. But even Taccola, a skilled engineer, appears to have been 
flummoxed by the design: he attempts a description of II Badalone only to 
find that his pen fails him. 'Let it be known that one cannot explain each 
and every detail,' he writes in some frustration. 'Ingenuity resides in the 
mind and intelligence of the architect rather than in drawing and writing.' 

Whatever the boat's design, its first and only known employment was 
the shipment of marble for the ribs of the dome. One year after the Opera 
had been forced to use tombstones in its building, Filippo acquired a 


Brunelleschi's Dome 



J. i 




f u 

20. Taccola's version of // Badalone. 

contract to transport 100,000 pounds of white marble from Pisa. With his 
ingenious new boat he calculated that he would reduce the shipping cost 
by almost half, lowering it from 7 lire and 10 soldi per ton to 4 lire and 14 

Not everyone was so optimistic. // Badalone appears to have been a 
source of ridicule from the start, a stick which Filippo's enemies, 
temporarily overawed by his astonishing success with the dome, now 
gleefully used to beat him. Most vocal of these was his old adversary 
Giovanni da Prato, who composed a sonnet attacking Filippo and his 
latest invention, which he described scathingly as an ac{]ue vola, or 'water 
bird'. This description implies that // Badalone, rather like a Mississippi 
steamboat, may have featured paddle-wheels, the sight of which, thrashing 
in the water like an awkward pair of wings, could have inspired Giovanni's 
insulting nickname. Such paddle-wheels, powered by treadmills, were 
certainly at a design stage a few years later. 


The Monster of the Arno 


21. A sketch of a boat with paddle wheels by the Sienese inventor 

Francesco di Giorgio. 

Giovanni's ill-humoured piece of verse makes his earlier comments 
regarding the faulty profile of the dome seem positively tame by 
comparison. He not only mocks the famous capomaestro as a 'pit of 
ignorance' and a 'miserable beast and imbecile', but furthermore promises 
to commit suicide should Filippo's plan succeed. Filippo was not one to 
suffer such discourtesies in silence. Fde may not have been a man of letters 
of the same stature, but he was no stranger to literary pursuits, as his study 
of Dante proves. He composed a sonnet of his own, equally caustic, in 
which he derided his distinguished opponent as a 'ridiculous-looking 
beast' who was incapable of understanding the mysteries of nature in his — 
Filippo's — ingenious designs. These exchanges became so rancorous that a 
short time later Filippo was among the citizens of Florence made to swear 


Brunclleschi's Dome 

an oath to 'forgive injuries, lay down all hatred, entirely free themselves of 
any faction and bias, and to attend only to the good and the honour and 
the greatness of the Republic, forgetting all offences received to this day 
through passions of party or faction or for any other reason'. It was an 
oath that, in the years to come, Filippo would find difficult to keep. 

In the end, Giovanni da Prato was not required to carry out his grisly 
promise to kill himself. Problems taxed the enterprise from the start. 
Although the patent was granted in 1421, // Badalone did not make her 
maiden voyage for another seven years, by which time the patent, originally 
for three years, had needed to be renewed at least once. In the summer of 
1426 Filippo travelled to Pisa to confer with the Consul of Maritime 
Affairs regarding the heightening of the city's fortifications. It seems likely 
that he took the opportunity to negotiate over // Badalone, for the Consul 
of Maritime Affairs inspected boats and merchandise passing through Pisa 
and issued permits for all crafts using the Amo. II Badalone was possibly 
even built in Pisa, which had long been renowned for its shipwrights. The 
galleys of the new Florentine navy — the first of which had sailed for 
Alexandria in 1422 — were at that time under construction in its dockyards. 
In any case, one day in early May 1428 Filippo's revolutionary new boat, 
laden with 100 tons of white marble, was launched from the dock at Pisa, 
in the shadow of another, leaning, technological folly. 

It is not clear whether disaster struck because of a design flaw, the 
Arno's treacherous sandbanks and currents, or some other mishap: the 
precise details of II Badalone's fate have not been recorded. We do know 
that the boat not only failed to reach Florence, it did not even make Signa. 
It either sank or became stranded near Empoli, 25 miles from Pisa, with 
the loss of its entire load. Shortly thereafter anxious officials from the 
Opera notified Filippo that he was 'required within eight days ... to ship 
by small boats to the Opera that quantity of white marble which he had 
shipped on the Badalone from the city of Pisa to Empoli'. 

The order was not executed within the time stipulated. Two months 
after the abortive journey Filippo was purchasing a 240-pound rope with 
which to salvage either the stricken vessel or her cargo — a humiliating 


The Monster of the Arno 

spectacle that Giovanni da Prato must have contemplated with relish. How 
Filippo attempted to recover the load from the bed of the Arno is not 
known, but a sketch by Taccola shows two stone-laden barges being used 
to raise a sunken marble column. Such salvage operations exercised the 
ingenuity and imagination of a number of engineers during the fifteenth 
century, leading to several attempts to design diving suits. Both Taccola 
and Francesco di Giorgio invented various types of breathing apparatus 
and underwater mask, as well as inflatable bladders to raise and lower 
divers. These works bore fruit in 1446 when, m one of the most celebrated 
engineering feats of the centur^^ Alberti raised part of the hull of one of 
Caligula's ships from the bottom of Lake Nemi by using divers from 

Filippo, however, met with no such success on the Arno. Almost four 
and a half years later the Opera was still pressing him to fulfil his contract 
to bring the errant 100 tons of marble to Florence — still, optimistically 
enough, on II Badalone, which must have survived the wreck. In March 1433 
Battista d' Antonio was forced to resort to the old and unsatisfactory 
expedient of cutting up tomb slabs for use on the dome. And that summer 
the Opera finally lost faith in Filippo and his wayward vessel, negotiating 
instead with three other contractors, who promised to deliver 600 tons of 
marble to Florence at a cost of 7 lire 10 soldi per ton — almost double 
Filippo's proposed price. 

Filippo had built II Badalone and contracted for the load of marble 
entirely out of his own pocket. Altogether he lost 1,000 florins on the 
venture — the equivalent of ten years of his salary as capomaestro and roughly 
one-third of his total wealth. It must have been a cruel blow for a man 
who had envisioned reaping lucrative financial rewards from his invention. 
Even worse, his reputation as the modem Archimedes was tarnished — a 
reputation that would be undermined still further a few years later, when 
another of his clever plans was to rebound disastrously. 


Debacle at Lucca 

A FEW WEEKS BEFORE // Badalone weighed anchor, Filippo had 
ridden on horseback into the nearby hills in order to oversee the 
extraction of yet more sandstone from the Trassinaia quarry. The 
dome had by this time reached a height of over loo feet, meaning that the 
teams of masons were now working 270 feet above the ground, or the 
equivalent of 20 storeys in the air. As the shells curved ever inwards they 
began preparing to install the third of the sandstone chains. The beams 
started arriving in the Piazza del Duomo at the beginning of i^k^. In 
preparation for laying them, Filippo's castello was refurbished with a new set 
of pulley wheels. 

Despite the embarrassing catastrophe of II Badalone, the Opera del 
Duomo still displayed confidence in Filippo's inventions and designs. The 
rota magna, the old treadmill built in 1396, was decommissioned and sold, 
having been rendered obsolete by the powerful new ox-hoist. Also sold 
was the timber used for the centring of the vaults in the tribunes. This 
latter act in particular revealed just how much faith Filippo inspired in the 
wardens. Deeply sceptical of his plans a decade earlier, they were now 
clearly convinced that the cupola could be raised without the use of a 
wooden centring. The evidence was, after all, right before their eyes in the 
shape of the half-finished dome. In fact, so confident had they become, 


Debacle at Lucca 

that Neri di Fioravanti's 1367 model of the cathedral, once so sacred, now 
served the Opera as a lavatory. 

Work on the third sandstone chain did not proceed quite as expected, 
however, and it would not be completed for another four years. The dome 
project was about to encounter its first serious delay. Construction first 
began to slow down when, in the summer of 1429, cracks were discovered 
in the side walls at the east end of the nave — that is, the end of the nave 
nearest the dome. Barely a year after the failure of // Badalone, Filippo 
suddenly found himself faced with a potentially more serious disaster. It 
seemed that the church, as constructed, might simply be unable to support 
the heavy load of the dome. 

There were no immediate signs of panic in the Opera del Duomo. 
Filippo was consulted by the wardens and, bold as ever, put forth one of 
his typically audacious proposals: he viewed the cracking walls as an 
opportunity to remodel the entire cathedral. What he now envisioned was 
a building different from the 1367 model but one that imitated another of 
Neri di Fioravanti's designs instead: that of Santa Trinita, the Gothic 
church beside the Arno that had been reconstructed by Neri on the site of 
a much older structure. Following Neri's design, Filippo proposed to flank 
the side aisles of the cathedral with a series of chapels. 

Filippo had already built or planned a number of such chapels in 
various of Florence's churches, including the Barbadori Chapel in Santa 
Felicita and the Ridolfi Chapel in San Jacopo. And in 1428 he had begun 
rebuilding the Augustinian church of Santo Spirito, which he planned to 
encircle with no fewer than thirty-six chapels, each belonging to a different 
family. It was the tradition in Florence for the bones of the wealthy to 
reside in splendour in special chapels within the churches (while those of 
Florence's poor were piled in the charnel-house). The remains of the 
Medici family lie in San Lorenzo, the Pazzis' in Santa Croce. In fact, 
Florence's churches were so crammed with tombs that during the fifteenth 
century one bishop voiced concerns about so many corpses defiling the 
Fiouse of God. His worries might also have been justified on the grounds 


Brunellcschi's Dome 

of public health: in times of plague it was always the houses nearest the 
churches that were the first to become infected. 

The chapels that Filippo was proposing for Santa Maria del Fiore 
would do more than serve as repositories for the bodies of Florence's finest 
citizens: they would form what he called a catena totius ecclesk, or a 'chain 
around the church'. Like the flying buttresses on the sides of Gothic 
cathedrals, they were to serve as abutments, bracing the walls of the nave 
against the outward thrust caused by the weight o{ the dome. Filippo 
assured the wardens that Santa Maria del Fiore would also be made much 
more beautiful as a result. 

In September 1429 Filippo was ordered to begin work on a model. The 
wardens were interested not only m how the chapels might stabilise the 
cathedral but also how they could be incorporated into its existing 
structure, the external walls of which were already encrusted with marble 
and decorated with sculpture. Would all of this painstaking artistry have 
to be refurbished or removed? And at what expense to the Wool Guild? 
Work had barely begun on this new model, however, when another 
distraction arose. In November 1429 Florentine mercenaries attacked 
Lucca, the wool- and silk-weaving city 40 miles to the west. It was to be an 
unexpectedly long and damaging campaign. 

For so long prey to both plagues and wars, Florence had enjoyed a brief 
respite for the first few years of the dome's construction. A war with the 
Kingdom of Naples had ended in 1414 when, in one of those miraculous 
events to which the Florentines were becoming accustomed, an earthquake 
shattered Naples and the enemy warlord King Ladislaus died o^ a 
fever. For the next ten years Florence experienced a period o^ peace, but 
then in the summer of 1424 Florence went to war once again. 
This time the enemy was the new Duke o^ Milan, Filippo Maria 

Filippo Maria was as formidable a ^ot as his late father, that ruthless 
enemy of Florence, Giangaleazzo. And he was demented even by the 


Debacle at Lucca 

standards of the Visconti family. Terrified of thunder, he would cower in 
a sound-proof room during storms, while m better weather he enjoyed 
rolling naked in the grass. Gluttonous and obese, he was unable to mount 
a horse or even walk unaided, and so sensitive was he about his ugliness 
that he refused to have his portrait painted. His second wife was 
imprisoned after the duke, a superstitious man, heard a dog howl on their 
wedding night. Her fate was preferable, however, to that of his first bride, 
who had been beheaded. 

Filippo Maria picked up where his late father had left off: in 1422 his 
troops captured both Brescia and Genoa, and a year later they seized the 
town of Forli, only 50 miles from Florence. The following year, as plague 
raged through Tuscany, his forces defeated the Florentines at Zagonara, in 
Romagna. There were only three casualties, all Florentine soldiers who fell 
from their horses and drowned on the battlefield m their heavy plate- 
armour (it had rained heavily in Zagonara the night before). This lack of 
bloodshed shows that warfare in the Middle Ages and Renaissance, 
contrary to popular conceptions, could be reasonably civilised. Most 
battles resembled chess matches in which opposing commanders sought to 
outmanoeuvre each other, the loser being the one who conceded that his 
position was technically vulnerable. These engagements were fought by 
mercenaries who settled the terms of warfare in advance, rather like 
sportsmen deciding the rules of a game. As a notary for the Commune, 
Filippo's father had frequently been involved in these negotiations, 
travelling far afield to engage the services of mercenaries such as the 
Englishman Sir John Hawkwood, who had commanded the Florentine 
army between 1377 and 1394. By common agreement the armies declined to 
fight in certain conditions: at night, in winter, on steep slopes or on boggy 
ground. The engagements were not always quite so congenial, however: six 
months after Zagonara the Florentines lost an entire army against the 
Milanese at Valdilamone. 

The battles against Lucca were even more disastrous. A truce had been 
signed with Filippo Maria m April 1428, when, to celebrate the occasion, 
torches were burned on the walls of Santa Maria del Fiore. But the ink was 


Bmnelleschi's Dome 

barely dr)- on the treaty when the Florentines set their sights on their 
neighbour. Like many medieval cities, Lucca had suffered a chequered 
past, passing from the hands o£ one warring state to another. In the 
previous hundred years it had been occupied by the Bavarians, sold to the 
Genoese, seized by the King of Bohemia, pawned to Parma, ceded to 
Verona, and finally sold to Florence. Now war was advanced bv the 
Florentines on the pretext that Lucca's ruler, Paolo Guinigi, had secretly 
been supporting the Duke of Milan. The campaign went badly from the 
outset, with the Republic soon getting bogged down in an unsuccessful 
war against a smaller and weaker foe. After several months of stalemate the 
Dieci della Balia (the War Office) decided to unleash their secret weapon: 
in March 1430 Filippo Brunelleschi was sent into the field. 

It was by no means unusual for an architect to become involved in a 
military c ampaig n during the \hddle Ages. Besides the cathedral in 
Florence, the Opera del Duomo was responsible for all military 
architecture within the Florentine domains. The men who built Santa 
Maria del Fiore were therefore the same ones who fortified Florence and 
its neighbours with walls, moats and bastions. Some ten years before 
starting work on the foundations of the new cathedral, Arnolfo di 
Cambio began raising a set of defensive walls around Florence. These 
massive fortifications were completed by Giotto in the 1330s. Two 
centuries later Michelangelo would rebuild these walls, raising bastions 
around San Miniato with unbaked bricks made from hemp and dung. And 
Leonardo da Vinci was forever drawing plans for weapons of war, 
including scythed chariots, steam cannons and gigantic crossbows. 

Like Arnolfo di Cambio and Giotto, Filippo was expected to carry out 
military commissions as a regular part of his duties. It was a busy time to 
hold the post of capotnaestro, for during the 1420s towns throughout 
Tuscany were being buttressed as protection against the mortars and siege 
engines of the Milanese. Filippo was involved in fortifying Pistoia as early 
as 1423, and a year later he began work at Malmantile, a stronghold in the 
Arno valley between Florence and Pisa. This fortress was completed two 
years later, when parapets, battlements, towers and a moat were in place. 


Debacle at Lucca 

Unlike many of Filippo's other architectural commissions, this stronghold 
was of a fairly traditional design. It operated on the time-honoured 
principle that any assailants who survived the hail of arrows and crossbows 
fired from the walls, and then managed to cross the moat, would be 
crushed to death by large stones dropped from the parapets. 

These were all defensive manoeuvres, however. What was required in 
1430 was an offensive weapon — some means of subduing the stubborn 
Lucchese once and for all. Mortars were being fired at Lucca from a 
distance of 1,200 feet, and the city's walls had been badly damaged. But 
still the Lucchese failed to relent. 

The technology of warfare was undergoing a transition during the 
fifteenth century. Gunpowder — seen by many as a devilish invention — had 
been introduced in the previous century, and large-calibre cannons were 
being cast, along with projectiles weighing several hundred pounds. 
However, since the formula for gunpowder (a mixture of saltpetre, sulphur 
and charcoal) had yet to be perfected, ancient and medieval devices such as 
siege engines, catapults and battering-rams were still in widespread use. 
Plans for both sorts of weapons are shown in a manuscript from the 1430s, 
De machinis, written by Filippo's friend Mariano Taccola. This treatise 
includes diagrams and descriptions of traditional devices such as 
articulated siege ladders and a bewildering array of catapults for hurling 
boulders at the enemy. There are also bombards and barrels filled with 
gunpowder and equipped with fuses. One of Taccola's most celebrated 
designs involved exploding a keg of gunpowder in a tunnel excavated 
under an enemy stronghold (a ploy that would re-emerge at the Battle of 
the Somme in 1916). No direct evidence exists of Filippo's collaboration on 
these designs, but scholars have speculated that the capomaestro may have 
originated at least some of them. Certainly a number of the catapults — 
loaded by hoists and powered by counterweights — were well within 
Filippo's widely recognised area of expertise. However, his plans for 
subduing Lucca involved something much more ambitious. 

Lucca had been the first city in Tuscany to adopt Christianity. 
According to legend it had been converted by St Frediano, an Irish monk 


Brunelleschi's Dome 

who saved the city from flooding by diverting the dangerously swollen 
River Serchio. Perhaps inspired by this legend, Filippo proposed to reverse 
the saint's miracle by altering the course of the Serchio and stranding 
Lucca in the middle of a lake contained by a dam. Cut off from the 
countryside, the Lucchese would have little recourse but to surrender. 

Filippo's plan was not an original one. Hydraulic engineering was used 
in warfare even in ancient times. In 510 BC, for instance, Milo, the ruler of 
Croton and patron of Pythagoras, diverted the River Crathis and flooded 
the warring town of Sybaris, an ancient city in southern Italy which 
archaologists have only recently uncovered. Some two hundred years later 
Sostratus of Cnidus captured Memphis for Ptolemy I, the King of Egypt, 
by changing the course of the Nile and dividing the town in two. More 
recently a Florentine engineer named Domenico di Benintendi had 
constructed for Giangaleazzo Visconti a number of gigantic dykes with 
which the duke hoped to redirect the River Mincio and flood the city of 
Mantua under 10 feet of water. The plan was never put into effect, though 
the remains of one of these dykes may still be seen at Valeggio. 
Fortunately, the duke was also unable to carry' through another of his 
ambitious plans: to drain the canals of Venice, thereby rendering the 
Venetians defenceless. 

Filippo appears to have acquired some expertise in hydraulic engineer- 
ing a short time before the Lucca project. During the late 1420s he 
travelled to Siena to consult with Taccola, whose speciality it was. 
F^lydraulics enjoyed a long tradition in Siena, where the shortage of water 
had been remedied by the construction during the Middle Ages of the 
bottini, 16 miles of underground tunnels, complete with filters and settling 
tanks, that conveyed fresh water to the city. During Taccola's time this 
supply of water was being increased and numerous fountains built. 
Taccola's De ingeneis showed how to build dams, bridges, flood controls, 
underwater foundations, aqueducts and various other waterworks. As we 
have seen, this treatise also depicted and attempted to describe // Badalone. 

In a manuscript discovered at the end of the nineteenth century, 
Taccola records a conversation with Filippo that took place during this 


Debacle at Lucca 

visit to Siena. Although Filippo is not known to have had any practical 
experience of hydraulic engineering before the Lucca project, he 
nevertheless speaks with some authority on the subject, exchanging ideas 
with Taccola on the best means of building dams and bridges. Special 
attention was given to sinking their foundations. Filippo warned Taccola 
that if the river bed consisted of large pieces of tufa — the lightweight, 
porous rock that the capomaestro had considered using in the upper part of 
the dome — it was better not to drive piles, since they would break the tufa 
and cause the water to flow through, carrying away the dam or bridge. 
These words of caution turned out to be lamentably ironic. Despite 
Filippo's theoretical preparations for the project, his enormous dam was a 
failure. Indeed, the Lucca disaster would be much more harmful to 
Filippo's reputation than the wreck of II Badalone. 

Work on the project proceeded slowly due to a lack of funds. Then 
doubts were raised about the strength of the dam even before it was 
completed. In May 1430 the notar\^ in the Florentine camp outside Lucca 
wrote to the War Office that after studying Filippo's design he remained 
unconvinced that the dam could withstand the weight of the water. But his 
arguments were skilfuUv parried by the capomaestro: 'To everything Pippo 
replies with arguments I cannot contradict,' wrote the flustered notary, 
'though I do not know if this is because I do not know more of this 
matter. Soon we shall see what will come of all of this.' 

Others in the Florentine camp were even more pessimistic about the 
project. Rather than arguing with Filippo, as the notarv had done, Neri 
Capponi, the commissioner for the Florentine army, simply sent his men 
to inspect the dam and make up their own minds about its robustness. 
Apparently one did not need to be an expert in hydraulics m order to 
realise that Filippo's plan was ripe for miscarriage. 

Filippo ignored these warnings, evidently unchastened by his humiliat- 
ing disaster with II Badalone, whose cargo, these two years later, he was still 
attempting to recover. His stubbornness on the issue was the result of his 
usual contempt for his critics. After all, had not his designs for the dome 
been mocked in the same way? And was not the dome, by all accounts, a 


Brunelleschi's Dome 

great success? In his conversation with Taccola he had condemned the 
capocchis et ignorantihus ('blockheads and ignoramuses') who could not 
understand the schemes of inventors like himself: 

Every person wishes to know of the proposals^ the learned and the ignorant. The learned 
understands the work proposed — he understands at least something, partly or fully — but 
the ignorant and inexperienced understand nothing not even when things are explained to 
them. Their ignorance moves them promptly to anger. They remain in ignorance because 
they want to show themselves learned, which they are not, and they move the other 
ignorant crowd to insistence on its own poor ways and to scorn for those who know~ 

The only thing to be done with such idiots, he claimed, was to march 
them o{{ to war. These remarks were recorded before the Lucca enterprise: 
after the debacle his plans for his critics may have been even less charitable. 

Like the Florentines, the Lucchese must have realised that Filippo's 
project was far from foolproof. Initially they countered the attempt to 
flood the plain by building dams of their own, raising a number of high 
embankments that prevented the water from flowing in the planned 
direction. But the Lucchese were not content with these defensive 
manoeuvres, and so one night, in a brilliant military sortie, one of their 
garrisons sneaked into Florentine territory and breached the canal that 
Filippo had dug at its point of deviation from the Serchio. The plain 
around Lucca was flooded, just as Filippo had predicted. However, the 
result was (as Machiavelli would sardonically remark in his history of 
Florence) 'contrary to his expectations': with devastating force the waters 
of the river swept away the dam and, worse still, flooded the Florentine 
camp. Instead of attacking Lucca, as planned, the Florentines were forced 
to beat a hasty retreat on to higher ground. Besides his reputation as an 
engineer, Filippo left behind something else on the swamped field outside 
Lucca: the tax reports for 1431 reveal that he lost his bed, which had been 
kept in his tent in the Florentine camp. 

The war went from bad to worse. Eager to weaken Florence, the Duke 
of Milan dispatched troops to Lucca. The Florentines countered by 


Debacle at Lucca 

bribing the duke's military commander, Count Sforza, to quit the city. 
Sforza duly departed from Lucca, but in the battle that followed, the 
Florentines were soundly defeated. Morale ebbed swiftly away. 

Filippo was not alone in being blamed for the defeat. A familiar 
scapegoat was used to explain the Florentines' ineptness in battle: 
homosexuality. For years clergymen such as the Franciscan firebrand 
Bernardino of Siena had been raging from the pulpit that the crime of 
sodomy was destroying the city. So famous was Florence for homosexual 
activity that during the fourteenth century the German slang for 
'sodomite' was Florenzer. In 1432 the government took steps to curtail this 
perceived root of its troubles on the battlefield by establishing an agency to 
identify and prosecute homosexuals, the Ufficiali di Notte, or 'Office of 
the Night' (a name made even more colourful by the fact that notte was 
slang for 'bugger'). This vice squad worked in tandem with the Orwellian- 
sounding Ufficiali dell'Onesta, or the 'Office of Decency', which was 
charged with licensing and administering the municipal brothels that had 
been created in the area around the Mercato Vecchio.* The specific aim 
of these public brothels was to wean Florentine men from the 'greater evil' 
of sodomy. Prostitutes became a common sight in Florence, not least 
because the law required them to wear a distinctive garb: gloves, high- 
heeled shoes and a bell on the head. 

Despite these measures the Florentines fared little better on the 
battlefield. The Duke of Milan persuaded Genoa, Siena and Piombino to 
enter into a league against the battered Republic. Seeing the writing on the 
wall, the Florentines sued for peace, and a truce was finally signed in 1433, 
though hostilities with Milan would not really end until the duke's death 
over a decade later. 

* A less official method of detecting homosexuals was for mothers to rattle their sons' 
coin bags: if the coins exclaimed 'fire, fire, fire' the money was said to be the gift of a 


From Bad to Worse 

THE WAR AGAINST Lucca took a severe toll on the building site 
at Santa Maria del Fiore. As the campaign began, the wages of 
most of the masons were halved, with some salaries falling much 
more drastically, from i lira per day to a positively stingy i lira per month. 
Even Filippo himself faced a pay cut: his salary dropped from loo florins 
per year to 50. Then in December 1430 over forty masons on the building 
site and in the quarries at Trassinaia were made redundant, partly because 
of the cold weather but also in order to save money. Construction 
throughout Florence had ground to a halt as funds intended for various 
buildings (including the oratory of Santa Maria degli Angeli, another of 
Filippo's projects) were diverted to the war effort. As commissions dried 
up, many artists, including Donatello, left Florence for more peaceful, 
prosperous cities. 

Given this belt-tightening regime, Filippo had selected a truly 
unfavourable moment to press his expensive plan to remodel the cathedral 
with a ring of chapels. Predictably his model met with little enthusiasm 
among the wardens, who decided to go for a cheaper option and reinforce 
the nave of the church with visible iron tie rods. Filippo accepted their 
decision, but only grudgingly. At the beginning of 1431 he designed a 
model for these rods and subsequently won the commission to install 


From Bad to Worse 

them. Within a month of this commission a significant decision was taken 
by the wardens: they ordered that Neri di Fioravanti's 1367 model should 
be destroyed. The cupola, they reasoned, was now 'beyond all comparison' 
with Neri's model. This was not to say that Filippo had violated the 
model, but that, with the structure so close to completion, Neri's model 
had lost Its function as a touchstone and building could continue without 
any further reference to it. 

In the end, both iron and wooden ties were used to prevent further 
cracks in the nave. Owing to his lack of enthusiasm for this solution, 
Filippo proceeded at a fairly leisurely pace in their installation, and in May 
1433 the wardens had to order him to hurry up. A year later, after the work 
was completed, he complained about their ugliness in a submission to the 
Opera. He believed that if his proposed chapels were built these eyesores 
could be removed, and so once again he began pressing the wardens to 
reconsider his plan. Although they allowed him to complete his abandoned 
model, their final answer was categorical: he was to forget his ring of 
chapels and concentrate instead on completing the dome. The wardens, 
understandably, were impatient to see the structure finished. They had 
been hoping to hold services under the cupola in 1433, but this timetable 
had been grossly optimistic and eighteen months later, when they came 
together to discuss Filippo's model for the chapels, the date of completion 
seemed no nearer. 

This episode marks one of the few times that Filippo was unable to wm 
over the wardens to his point of view. But his annoyance must have been 
eclipsed by other, more pressing worries, for in August 1434, just a few 
days after the meeting of the wardens and Wool consuls, he was arrested 
and thrown into prison. His crime: failing to pay his annual dues to the 
Masons Guild. His life seemed to be going from bad to worse. 

The Arte dei Maestri di Pietra e di Legname, the ' Guild of Stonem asons 
and Carpenters', was one of the largest of the Florentine guilds. It was run, 
like the other guilds, not so much for the benefit of its members — the 
common labourers and stonemasons — as for the political elite of the city. 


Brunelleschi's Dome 

The guilds were the nominal foundation o{ the Republican constitution, 
because membership in one of them was a qualification for any political 
office. But power had actually come to be concentrated in the guild court 
of the Mercanzia, which had been founded in 1309 and was controlled by a 
network o{ wealthy, intermarrying and often rival families, including the 
Capponi, the Medici, the Strozzi, the Bardi and the Spini. Through the 
Mercanzia this economic elite extended its power into the running of the 
other guilds, controlling the selection of candidates eligible for guild 

In the Middle Ages the Masons Guilds of northern Europe had become 
the jealous guardians of the 'mysteries' of their profession. In a famous 
case from 1099, for example, the Bishop of Utrecht was murdered by a 
master mason whose son he had persuaded to reveal the secret of laying 
out the foundation of a church. There were, of course, obvious reasons for 
maintaining a monopoly on this sort of information: the masons had an 
economic interest in not disseminating their knowledge beyond the guild. 

In Florence, however, the Masons Guild was never so obsessively 
jealous of its secrets. It was possible not only for carpenters and masons 
from outside Florence to practise their craft within the city but also for 
craftsmen from other guilds to work in the building trade. The guild did 
not seem anxious to require membership of such men, much less dues. 
Neither Giotto nor Andrea Pisano, two previous capotnaestri, ever joined it. 
Filippo had even been granted an exemption that permitted him to work 
as an architect without having matriculated in the guild, a fact that made 
the sudden demand for membership dues — and his arrest — all the more 

Filippo's arrest is certainly suspicious. The dues for one year would 
have amounted to the grand total of 11 soldi, or roughly the amount that a 
common labourer on the site of Santa Maria del Fiore could earn in a 
single day of work. Surviving records show that, despite this modest rate, 
the accounts of many members of the guild were in arrears. But only 
Filippo was ever arrested and imprisoned for nonpayment. Clearly sinister 
forces were at work to ruin the capomaestro. 


From Bad to Worse 

Filippo had been politically active in Florence throughout the course of 
his work on the dome, serving numerous times on the councils that passed 
and rejected legislation proposed by the Signoria." But he was rapidly falling 
out of favour with the Florentine rulmg class. What was more, his wealthy 
patron Cosimo de' Medici — the man whose family had commissioned 
him to rebuild the church of San Lorenzo in 1425 — was now in exile. 
Cosimo's departure was a blow to the artists of Florence. After the death 
of his father, Giovanni, in 1429, he had become head of the powerful 
Medici bank. A learned man, Cosimo read Greek philosophy, collected 
ancient manuscripts and coins, befriended the humanist scholars and, 
following the example of the ancient Romans, rose early each morning in 
order to tend to his orchards and vineyards. F^is political career was a little 
less idyllic, however. F4e had been one of the members of the War Office 
who prosecuted the unsuccessful campaign against Lucca and m the wake 
of this failure he was arrested on a trumped-up charge of plotting to 
overthrow the government. In September 1433 he was imprisoned in the 
tower of the Palazzo della Signoria and shortly afterwards banished to 

Like Cosimo, Filippo was in a weakened state following the disaster on 
the battlefield at Lucca. F^is reputation had been damaged, his most 
powerful patron was in exile and his work on the dome — though 
proceeding successfully — had been slowed due to a shortage of both 
manpower and funds. It was at this moment, therefore, that his enemies 
chose to pounce. The man behind his imprisonment was Ravnaldo 
Silvestri, one of the consuls of the Masons Guild. It is tempting to ask if 
Silvestri was acting for anyone else besides the guild consuls. What, for 
example, might have been the role of Lorenzo Ghiberti or Giovanni da 
Prato? Lorenzo was immune from arrest on a similar charge, for he had 
joined the Masons Guild eight years earlier after having worked in the 
profession for almost a decade while stiH a member of the Silk Guild, to 
which Filippo also belonged. Late in life he would become a pillar of his 
new guild, serving as a consul between 1449 and 1453. But no evidence 
exists to suggest that the arrest was an intrigue on his part. It is more likely 


Brunelleschi's Dome 

that it was instigated at the behest of the same people — the powerful 
Albizzi faction — who had engineered the exile of Cosimo de' Medici. 

All things considered, Filippo's incarceration could have been much 
worse than it was. He was not held like a common criminal in Florence's 
communal prison, the Stinche, nor in the artificial underground caves, the 
hurelle, that served as Florence's dungeons. The populations of these 
prisons consisted mainly of paupers unable to pay fines levied against 
them, as well as forgers, adulterers, thieves and gamblers. It was to this 
former prison, which stood near the Piazza Santa Croce, that Manetto, the 
Fat Carpenter, had been brought as part of Filippo's scheme against him. 
Also held in the Stinche were more serious criminals — heretics, sorcerers, 
witches and murderers — for whom unpleasant fates awaited: decapitation, 
amputation or burning at the stake. Executions took place outside the 
walls, in the Prato della Giustizia, the 'Field of Justice'. These were 
popular public spectacles — so popular, in fact, that criminals often had to 
be imported from other cities to satisfy the public's demand for macabre 

Filippo enjoyed a somewhat happier time. He was confined inside the 
prison of the Mercanzia, which was located in the Piazza della Signoria, 
and soon after his imprisonment the wardens of the Opera came to his 
rescue. Furious at his treatment, they insisted that the Capitano del 
Popolo, Florence's chief of police, arrest Raynaldo Silvestri. Filippo was 
released from prison a few days later, on 31 August, having spent the better 
part of two weeks in confinement. On the following day a pro-Medici 
government was elected, Cosimo recalled from Venice and Rinaldo 
Albizzi — leader of the rival faction — sent into exile. But if Filippo 
thought that his problems were over and he could now concentrate his 
efforts solely on the cupola, he was sadly mistaken. Less than two months 
later, in October, his adopted son, Buggiano, stole money and jewels from 
his house and fled to Naples. 

Andrea Cavalcanti, or *I1 Buggiano', had lived with Filippo for fifteen 
years, ever since he was brought to Florence at the age of seven. Filippo 


From Bad to Worse 

probably first met the boy in the Tuscan village of Buggiano, near Pistoia, 
where Ser Brunellesco, his father, had owned a plot of land with vines and 
olive trees. In 1434, Buggiano was already making his mark in Florence as a 
sculptor. Filippo had employed him on a number of prestigious projects, 
including the cathedral, for which he sculpted a marble lavabo, the ritual 
hand-basin in the south sacristy. Nearby in San Lorenzo he had worked 
on an even more prominent commission: the sarcophagus for Giovanni de' 
Medici and his wife Piccarda, the parents of Cosimo de' Medici. 

Little is known of Buggiano's early life, but his education and 
upbringing must have been similar to Filippo's, and he became a master in 
the Silk Guild at twenty-one. It was natural for a son in Florence to 
apprentice in his father's workshop. Lorenzo Ghiberti, who worked at the 
foundry of his stepfather Bartoluccio, would later be succeeded by his own 
two sons and then by his grandson Buonaccorso. Similarly, the capomaestro 
Battista d' Antonio was assisted in his work on the cupola by his son 
Antonio. In fact, Antonio would even be named as a capomaestro. What is 
odd about this latter arrangement — apart from the fact that yet another 
capomaestro was deemed necessary — is the fact that in 1430, the year of his 
appointment, Antonio di Battista was only eleven years old. At this tender 
age he was not even old enough to be apprenticed to a stonemason, let 
alone be put in charge of the century's grandest building project. Strange 
as it may seem, such an arrangement was not unprecedented. Minors were 
sometimes named as heads of industrial firms in Florence even though they 
had no actual input in the running of the business. In 1402 Cosimo de' 
Medici, then thirteen, was named head of the Medici's wool-manufactur- 
ing firm. Not surprisingly, the actual administration was left to an 
experienced manager. Similarly, the participation on the cupola project of 
Antonio di Battista, the hoy-capomaestro, seems to have been minimal and 
his position only nominal. 

Buggiano's position, whether at the cathedral or in San Lorenzo, was far 
from nominal. By executing commissions such as the sarcophagus for 
Giovanni de' Medici he freed Filippo to work on his designs and models 
for the cupola and also to seek out further work. Buggiano was, moreover, 


Brunelleschi's Dome 

a very skilled sculptor: at times his work is indistinguishable from that of 
Filippo, and at other times he even surpasses his master/ Filippo cannot 
have been an easy person to work for, given his volatile, demanding and 
stubborn nature. And, for whatever reason, he seems to have treated the 
young man rather casually. He failed, for example, to pay him the 
substantial sum of zoo florins — two years' worth of wages — for his work 
on the cathedral and in San Lorenzo. Buggiano therefore took the money 
and jewels as his remuneration and absconded to Naples, where he 
presumably planned to make his way in the world without the assistance 
of the capomaestro. 

Filippo should not have experienced any difficulties meeting this 
payment given the fact that in 1433, despite his losses over // Badalom, he 
was still worth the considerable sum of 5,000 florins. But the capomaestro, a 
genius in so many other areas, was not as skilled as he might have been at 
handling his finances. This tendency was not unusual, since a carefree 
attitude towards money was typical of many of Florence's great artists and 
sculptors. Filippo's friend Masaccio would make loans without bothering 
to collect them, and Donatello was said to have left sitting on his 
worktable a basket of money from which his apprentices were free to help 
themselves. Filippo could be equally generous, giving much of his money 
to the poor, but his casual attitude to his finances was sometimes not so 
much charitable as negligent. In September 1418, for example, his political 
career had suffered a temporary setback when tax arrears rendered him 
ineligible for office. His timing in that case could hardly have been worse 
given that the cupola competition had been announced only a month 

Buggiano was twenty-two when he absconded to Naples with Filippo's 
possessions. Although already a master carver, he was still deemed an 
adolescent by Florentine law. In fact, like all adolescents, he would not be 
emancipated from his father's authority until the age of twenty-four, and 
some of these 'adolescents' could even remain under the control of their 
fathers until they were twenty-eight. Little wonder that many of them 
chafed under this system: the fourteenth-century poet and storyteller 


From Bad to Worse 

Franco Sacchetti wrote that five out of six sons wanted their father to die 
prematurely so they could be set free. And it is in this role, that of the 
father betrayed by an ungrateful son, that we now catch a glimpse of 

The full details of this unflattering incident remain obscure because 
neither Vasari nor Manetti mentions it, just as they mention neither II 
Badalone or the failed scheme to flood Lucca. Whatever the situation, 
Filippo was determined to have both Buggiano and his property returned. 
Unlike his friend Donatello, who had pursued one of his runaway 
apprentices to Ferrara, bent on murder, he proceeded along strictly legal 
lines, appealing to the highest authority: none other than Pope Eugenius 
IV. The young man's theft and flight therefore turned into an 
international incident. 

Pope Eugenius had arrived in Florence in June, after being driven from 
the Lateran Palace by a stone-throwing mob of Romans made miserable 
and desperate from incessant warfare against the Duke of Milan, who was 
now harrying the Papal States. Eugenius had made his escape down the 
Tiber in disguise, sailed from Ostia, then disembarked at Livorno after a 
perilous journey. Altogether he would spend several years in Florence, 
where he would take part in a number of historic ceremonies in Santa 
Maria del Fiore. 

The Papal Abbreviator at this time was Leon Battista Alberti, who had 
accompanied Eugenius to Florence. In 1434 Alberti was writing De Pictura 
(*On Painting'), the Italian version of which he would dedicate to Filippo 
two years later, with its praise of the amazing feat of 'Pippo the architect' 
m raising the dome. As Abbreviator, Alberti had the task of composing all 
of Eugenius's letters and bulls in impeccable and elegant Latin. Normally 
these bulls concerned doctrinal and liturgical matters, but on the twenty- 
third of October Alberti found himself promulgating what must have 
seemed a rather irregular edict: a request that Queen Giovanna of Naples 
immediately send Buggiano back to Florence along with the money and 
jewels taken from Filippo's house. A request from such a source could not 
be taken lightly, and the runaway sculptor was promptly returned to 


Brunelleschi's Dome 

Florence and the custody of his master. The embarrassing episode was 
thereby brought to a conclusion. Buggiano went back to work in Filippo's 
studio, dutifully executing further commissions for his master. No further 
such disputes appear to have arisen between the two men, and soon 
afterwards Buggiano was named as Filippo's heir. 



RELIGIOUS FEASTS WERE numerous in Florence, averaging 
almost one per week. The populace was accustomed to grand 
spectacles on these occasions: to the sight of priests and monks in 
rich habits of gold and silk bearing through the streets the standards of 
their orders and their most prized relics, all to the tolling of bells, the 
blaring of trumpets, the chanting of songs and the splashing of holy water. 
But in 1436 the Feast of the Annunciation, observed on the twenty-fifth of 
March, was the occasion for a celebration that was spectacular even by the 
standards of Florence. 

On this day Pope Eugenius IV processed eastwards to the centre of the 
city from his residence in Santa Maria Novella. He was accompanied by 
seven cardinals, thirty-seven bishops and nine members of the Florentine 
government, including Cosimo de' Medici. The procession moved along a 
1,000-foot-long wooden platform, six feet in height, that was bedecked 
with sweet-smelling flowers and herbs. This gangway had been designed by 
Filippo to carry the Pope safely above the crowds teeming in the streets 
below, a method of crowd control evidently selected in place of a much- 
used alternative, that of throwing coins into the street in order to scatter 
the people and keep them from pressing too closely upon the Holy Father. 
As the entourage turned into the Via de' Cerretani and creaked across the 


Brunelleschi's Dome 

boardwalk in the direction of the thronging Piazza San Giovanni, the new 
cathedral rose suddenly into view. After 140 years of construction, the time 
had finally come to consecrate Santa Maria del Fiore. 

Annunciation Day was an appropriate occasion for such a ceremony. 
The feast celebrates the appearance o{ the Archangel Gabriel before the 
Virgin Mary. In most depictions of the Annunciation, Gabriel is portrayed 
holding a lily, the symbol not only of puritv but also of the cit\' of 
Florence. He delivers to the Virgin tidings of the miracle to come: the 
intrusion of the divine into the realm of the human. For the people of 
Florence in 1436 the new cathedral must likewise have seemed a feat of 
divine intervention — though in this case the miracle had been performed 
not by an angel but by a man. 

Santa Maria del Fiore had been carefully prepared for the ceremony. 
The makeshift wall dividing the octagon from the nave — a hoarding that 
separated the worshippers from the labourers — had finally been removed. 
A temporary wooden choir was erected according to Filippo's design and 
its twelve wooden statues of the Apostles given coats of paint. Linen 
curtains were fitted into the enormous windows of the drum in order to 
keep out the wind. Most noticeable of all, after fifteen years of almost 
continuous service the ox-hoist and its platform no longer stood in the 
middle of the octagon, which had now been paved with brick. 

As the ceremony began, a cardinal proceeded along the new choir, 
moving from one of Filippo's wooden Apostles to another, lighting a 
candle in front of each. Eugenius climbed the steps of the altar, which was 
the cue for the chorus to begin singing its motet: 

Lately the blossoms of roses, a gift from the Pope, 

Despite the cruel cold of wititer 

Adorned the great edifice of the cathedral 

Dedicated in perpetuity to thee, 

Virgin of Heaven, holy and sanctified . . . 

Eugenius meanwhile began placing all of the cathedral's relics on to the 



altar. Chief among these were the finger bone of St John the Baptist and 
the remains of the patron samt of Santa Maria del Fiore, Saint Zenobius, 
whose skull had been discovered in 1331 and placed inside a silver reliquary 
shaped like the dead saint's head.'^ As he did so, the cardinal began 
christening the red crosses in the hands each of the twelve wooden 
Apostles. By this act the cathedral was filled with the living presences of 
these saints, who were now capable, the Florentines believed, of working 
further miracles. 

Though work had proceeded swiftly in the two years smce Filippo's 
release from prison, the dome itself was not actually complete. In 1434 its 
walls had reached the required height of just over 144 hraccia, or some 280 
feet above the ground. A year later the masons had laid the fourth and 
final stone chain, which served as the closing ring at the top of the dome. 
But there was still much to be done. The exterior surface of the dome had 
yet to be tiled with terracotta, a task that would require another two years, 
and the facings of coloured marble would take more than another 
generation to complete. And the marble lanterna, or lantern (so called. 
because of its appearance), had to be designed and then erected on top of\ 
the dome. ^ 

In 1436, however, the time seemed ripe for celebration. Therefore, on 30 
August, five months after Pope Eugenius had consecrated the cathedral, 
the cupola itself was consecrated — a full sixteen years and two weeks after 
construction had begun. This ceremony was performed at nine o'clock in 
the morning by the Bishop of Fiesole, who climbed to the top of the dome 
to lay the final stone. Trumpets and fifes were played, church bells rang 
and the rooftops of the surrounding buildings were crowded with 
onlookers. Afterwards the capomaestri and the wardens descended from the 
cupola and indulged themselves with a meal of bread, wine, meat, fruit, 

* An even more prized relic had so tar eluded the Florentines: the skull of St John the 
Baptist. In 141 1 the Commune had negotiated to purchase it from the Antipope John XXIII. 
The deal fell through, however, so some thirty' years later the architect Filarete, acting as an 
agent for the Commune, tried to steal the skull and smuggle it to Florence. Caught in the 
act, he was sent to prison. 


Brunelleschi's Dome 

cheese and macaroni. The bulk o{ the enormous task lay behmd them. 
The people of Florence had at last been given the dome they had dreamt 
of for almost seventy years, and Filippo had succeeded m performing an 
engineering feat whose structural daring was without parallel. Against 
enormous odds, he had achieved all that he had hoped to achieve ever 
since, as a boy, he had walked past the domeless cathedral and watched the 
groaning treadwheels at work. Seeing the new dome soarmg over the cit)' 
he must have been overwhelmed by the feeling that he had equalled, and 
even surpassed, the Romans whose works he had studied and admired. 
More than that, he must have felt that everything he had been made to 
suffer for the past two decades — the ridicule, the rivalries, the intrigues of 
his enemies — had been swept away by the scale of his accomplishment. 


The Lantern 

MOST DOMES FROM the Renaissance onwards feature lanterns 
at their summits. These usually serve a practical as well as a 
decorative purpose, admitting light into the interior of the 
dome as well as promoting ventilation. Neri di Fioravanti's model had 
included such a feature, as did Filippo's 1418 version, but with both of 
these models demolished — Filippo's one year after Neri's — no definitive 
design for a lantern existed. 

Filippo must have felt by this point that the Opera del Duomo should 
automatically select him to design the lantern. But tvpically they 
announced another competition. In the summer o{ 1436 Filippo therefore 
began work on a model, as did Lorenzo Ghiberti and three other hopefuls. 
One can imagine Filippo's resentment: he would have been all too aware of 
the fact that, when Lorenzo finished the Baptisten^ doors in 1424, he was 
immediately commissioned to cast a further set — the 'Doors of Paradise' — 
without having to endure another competition. For Filippo the insult was 
no doubt worsened by the fact that one of his competitors for the design 
of the lantern was a lowly leadbeater. Another, worse still, was a woman. 
The size and form of the lantern had been under discussion for several 
years. They would depend in part on the base on which its substructure 
was imposed — the sandstone chain at the top of the dome. Not installed 


Brunelleschi's Dome 

until 1435, this chain had been the subject of considerable deliberation. As 
early as June 1432 a wooden model had been ordered by the Opera in order 
to determine its size and whether it should be octagonal like the first 
sandstone chain or circular like the arch-rings. Two months later the 
model was studied by the wardens, who selected an octagonal design but 
decided to reduce the diameter of the chain from 12 hraccia to 10, or roughly 
19 feet. A year later the diameter was again reduced slightly, this time to 
just under 10 hraccia. Giovanni da Prato cannot have been pleased with 
these shrinking dimensions, for now even less light would be admitted into 
the church. 

Filippo began constructing his model of the lantern with the help of a 
31-year-old carpenter named Antonio di Ciaccheri Manetti. Antonio (not 
to be confused with Antonio di Tuccio Manetti, Filippo's biographer) was 
well known to the capotnaestro. He had assisted Filippo with the wooden 
model of the closing ring, as well as with Filippo's design for the choir. 
The capotnaestro would draw sketches of the lantern and send them to 
Antonio's workshop near the cathedral. Very soon, however, he had reason 
to regret his choice of collaborator. According to the biographer Manetti, 
Filippo was a better architect than a judge of character, for Antonio 
betrayed him by constructing a model of his own in which he 
unscrupulously incorporated many features of Filippo's design. This was 
exactly the sort of plagiarism the capotnaestro had feared since the beginning 
of his career. But there was nothing to be done: Antonio's model was 
submitted to the Opera along with his own, Lorenzo Ghiberti's, and two 

On the last day of 1436 the wardens met to examine the five models. 
Perhaps aware that their decision could prove controversial, they consulted 
widely: masters of theology, doctors of science, masons, goldsmiths, 
painters and a mathematician, as well as various influential citizens, 
including Cosimo de' Medici himself— all were called upon to offer their 
opinions. Their judgement, in the end, found in favour of Filippo's design, 
stating that his model would make for a stronger, better lit and more 
waterproof lantern. The wardens did, however, attach an important clause 


The Lantern 

to their ruKng, commanding FiHppo to 'put aside all rancour remainmg m 
him' (obviously they knew him well) and accept a number of suggested 
modifications to his design, however insignificant they might seem. The 
reason for this qualification was that Antonio had appealed to the wardens 
to allow him to make yet another model. Evidently impressed by Antonio, 
they assented. 

Once again the carpenter went to work, this time producing a model 
that was an even closer replica of Filippo's. This model was none the less 
rejected by the wardens, at which point the capomaestro reputedly told them, 
'Fategliene fare un altro efara el mio — that is, 'Let him make another and he 
will make mine'. Thereafter the relationship between the two former 
collaborators deteriorated, culminating (as Filippo's battles so often did) 
with an exchange of insulting sonnets. The episode evidently erased from 
Filippo's memory his earlier vow to forgive injuries and lay down all 
hatred. Alas, the lines of wit and vitriol inspired by this conflict have long 
since been lost to the world. It is sadly ironic that although Filippo's plan 
prevailed, it was Antonio who had the last laugh: in 1452 he would become 
capomaestro of Santa Maria del Fiore, overseeing the construction of the 
lantern, complete with a number of his own alterations. 

Octagonal in shape, the lantern sits on a marble platform supported by 
the sandstone chain. Its eight buttresses rise in line with the eight ribs of 
the dome to support 30-foot-high pilasters crowned with Corinthian 
capitals. Between the pilasters are eight windows, each also 30 feet in 
height. The interior features a small dome above which a spire rises 23 feet 
to be topped by the bronze ball and a cross. Inside one of the buttresses 
(all of which are hollow in order to decrease the weight of the lantern) a 
stairway leads to a series of ladders which in turn lead up through the spire 
and into the bronze ball itself. This giant ball is fitted with a small flap- 
window that, at 350 feet above the streets, offers Florence's loftiest 

In all, over a million pounds of stone would need to be raised to the 
top of the cupola. Since the cathedral was now in use, it was impossible to 
have a large hoist at ground level. This meant the hoist had to be manually 


Brunelleschi's Dome 

operated from the working level and, therefore, small in scale — small 
enough, that is, for several men to operate in the limited space at the top 
of the dome. Yet it also had to be capable of raising marble blocks 
weighing as much as two tons. 

Only a few days after the cupola was consecrated, the Opera had 
announced yet another competition, calling for models of machines 'for 
hauling loads up on the great cupola'. Filippo, as usual, rose to the 
challenge. After building a model for a new hoist he was promptly granted 
the commission along with a prize of loo florins, the same amount with 
which he had been rewarded for his design for the ox-hoist many years 
earlier. Work on this new machine began in the summer of 1442 and was 
completed the following year. 

This new hoist was later sketched by Lorenzo Ghiberti's grandson 
Buonaccorso. A slightly less complex machine than the ox-hoist, it is 
nevertheless ingenious in design, featuring multiple pulleys, a counter- 
weight and a braking system. Buonaccorso's sketch includes a text written 
in cipher, albeit a fairly crude one. His code (known as the 'Caesar 
Alphabet' because of the fact that Julius Caesar reputedly invented it) 
simply replaces each letter in the alphabet with the one that precedes it: B 
with A, D with C, and so forth. Once decrypted, the text describes the 
operations of the machine's various parts. In keeping with his nature, 
Filippo had probably also attempted to guard the secrets of the hoist, 
especially after his experience with Antonio di Ciaccheri. 

The most interesting of the hoist's features was its braking system. 
Since the men powering the hoist would clearly not have the strength and 
endurance of the oxen that had driven Filippo's earlier hoist, it was 
necessary to design a system whereby both the load and counterweight 
could be suspended in mid-air if necessary. The vertical gear was therefore 
fitted with a ratchet wheel and a pawl that allowed the load to be locked 
into position. The gears were also much smaller than those in the ox-hoist, 
entailing a slower ascent for each payload. 

Work on the lantern was delayed because of a familiar problem: the 
difficulty of acquiring sufficient quantities of hianchi marmi. Quarries were 




'U'»*c«m- ^ji/«l»^ vef^ S'^T'vin^v^ -"lr-t--f. ^«»^>«*^-~' 


22. Buonaccorso Ghiberti's sketch of Filippo's lantern hoist. 

Brunelleschi's Dome 

examined near Campiglia as well as at Carrara, but the former proved 
inadequate because the town of Campiglia failed to provide Filippo's 
masons with working facilities. In the end, marble did not begin arriving 
from Carrara until the summer of 1443. It was brought to Florence by sea, 
river and road. Fifteen years after the wreck of II Badalone, Filippo, now 
sixty-six, appears to have washed his hands of this particular problem and 
it was left to Antonio di Ciaccheri to design and build a special cart to 
carry the marble from Signa to Florence. But Filippo did ensure that, once 
on the building site, the blocks of marble were protected from the bumps 
and scrapes of the new hoist by special wooden coverings. 

Over the next few years the Piazza del Duomo became so crowded with 
these blocks of marble — some of which weighed more than 5,000 pounds 
— that the people of Florence became alarmed at the thought of them 
stacked on the top of the cupola. Surely it was tempting fate to burden it 
with so massive a weight? Filippo dismissed these fears, claiming that, far 
from causing the dome to collapse, the lantern would actually strengthen it 
by acting as a common keystone for each of the four arches comprising 
the vault. 

Once the blocks of marble had been hoisted to the top of the cupola, 
they needed to be laid in their places, an operation requiring yet another 
machine. Construction of a crane for this purpose was begun in 1445. 
Some 20 feet high and 20 feet wide, this apparatus could not have been 
raised through the oculus, which was less than 19 feet in diameter; it 
therefore had to be constructed at the top of the cupola. Walnut logs, pine 
beams and bronze pins used to build the crane were all winched into the 
air and then assembled at the dome's summit. Although built under the 
direction of Antonio di Ciaccheri, who was making himself more and 
more indispensable to the Opera, the crane was, like all of the other 
machines used on the dome, the product of Filippo's ingenuity. 

As the lantern took shape it became clear that it was an aesthetic triumph. 
Most later lanterns, including the one built for St Peter's in Rome, would 
be based on its style. But it also left a more unexpected legacy. 


The Lantern 

Architectural marvels like Filippo's dome often become sites of 
scientific inquiry because their unique structures and dimensions can serve 
as testing grounds for new theories and technologies, Galileo would drop 
cannonballs from the Leaning Tower of Pisa in order to provide an ocular 
demonstration that all falling bodies descend with equal velocity 
independent of weight. Hundreds of years later Gustave Eiffel studied 
aerodynamics from the top of his tower (where wind speeds regularly 
reach well over loo miles per hour) and ultimately proved that the suction 
over the upper surface of an aeroplane's wing is more important to its 
flying abilit)'' than the air pressure beneath. The dome of Santa Maria del 
Fiore likewise aided scientific study, only in this case the knowledge gained 
was used, not for transport through the air but, rather, across the ocean. 

Paolo Toscanelli was one of the greatest mathematicians and 
astronomers of the century. It appears that he met Filippo in about 1425, 
and he would later call his friendship with the capomaestro the greatest 
association of his life. Like Filippo, Toscanelli was a lifelong bachelor and 
an unlovely physical specimen, with thick lips, a hooked nose and a weak 
chin. Although a wealthy man, he forsook all luxury and lived like a monk, 
sleeping on a wooden plank beside his work table and following a 
vegetarian diet. He had trained as a physician in Padua but spent most of 
his time gazing at the heavens and performing complex mathematical 
calculations. He instructed Filippo in the geometry of Euclid, and later the 
capomaestro would repay the favour, albeit unwittingly, by assisting him with 
his celestial observations. For in 1475, inspired by the height of the dome, 
Toscanelli climbed to the top and, with the blessing of the Opera del 
Duomo, placed a bronze plate at the base of the lantern. This was 
designed so that the rays of the sun would pass through an aperture in its 
centre and fall some 300 feet to a special gauge on the floor of the 
cathedral, a stone inlaid in the Chapel of the Cross. Santa Maria del Fiore 
was thus transformed into a giant sundial. 

This instrument would prove vital to the history of astronomy. The 
height and stability of the dome allowed Toscanelli to gain a superior 
knowledge of the sun's motions (or rather the earth's orbit around the 


Brunclleschi's Dome 

sun), which in turn enabled him to calculate with a much greater accuracy 
than anyone previously the exact moment of both the summer solstice and 
the vernal equinox. These calculations served an ecclesiastical purpose in 
that religious dates such as Easter could be carefully regulated, but they 
also had more far-reachmg applications. 

After Prince Henry the Navigator founded his school for mariners at 
Sagres in 1419, the Portuguese had undertaken a number of voyages of 
discovery in the eastern Atlantic, using a new type of vessel called the 
caravel, a light, swift ship designed to sail into the wind. The fruits of 
these voyages were manifold. Portuguese navigators sponsored by Prince 
Henry had explored the two remotest islands in the Azores (first 
discovered in 1427) and traced much of the coast of West Africa. The 
Cape Verde archipelago was sighted off the coast of Africa in 1456 and, 
fifteen years later, Portuguese sailors crossed the Equator for the first time. 
But larger prizes still lurked over the horizon. Islands such as Brasil, 
Antillia and Zacton all existed in legend, but no one had yet set eves on 
them. The latter of these islands was said to be especially rich in spices. 

These voyages into the Atlantic could not have been made without the 
aid of astronomy, which permitted mariners to navigate uncharted waters 
and then make maps of their discoveries. Navigation in a relatively small 
body of water like the Mediterranean was done by means of charts 
showing a scale of distances and a pattern of twelve rhumb lines (later 
expanded to sixteen) that radiated from a central point known as the wind 
rose. The navigator would simply trace a line between two points, then 
find the corresponding rhumb line — one running north-north-east, for 
example — and shape his course from it with the help of a magnetic 
compass. Questions of longitude and latitude could safely be ignored. But 
when Portuguese seamen ventured south into the uncharted waters along 
the west coast of Africa they discovered that this simple method was no 
longer applicable. The great age of celestial navigation was about to begin. 

Crucial to this type of navigation was the astrolabe, an instrument that 
astronomers used to calculate the position of the sun and other stars with 
respect to the horizon. By the middle of the 1400s it was being used by 


The Lantern 

mariners to calculate their positions on the ocean. As astronomical 
determinations of longitude were unreliable, accurate readings of north- 
south distances — determinations of latitude — were of great importance 
in both navigation and mapmaking. Mariners calculated their latitude by 
using the astrolabe to take angle sights on the Pole Star, measuring the 
angle between its direction overhead and the horizon. As they sailed closer 
to the Equator, however, the Pole Star sank lower in the sky and this 
method became impractical. The sun was therefore used instead, the 
astrolabe measuring its angle above the horizon at midday. 

This determination was a simple enough operation except for the fact 
that the position of the sun, like that of the Pole Star, does not coincide 
with the celestial pole. In other words, neither of these guides to celestial 
navigation lies directly on the imaginary extension of the Earth's axis from 
the North Pole. In order to obtain the latitude of an area it was therefore 
necessary to apply a correction to their observed altitudes. A number of 
tables of declination already compiled by astronomers were used for this 
purpose, most notably the Alfonsine Tables, which had been prepared by 
Jewish astronomers in Spain in 1252. These tables enabled astronomers and 
navigators to calculate the positions of the sun and the Pole Star 
throughout the various seasons, as well as lunar or solar eclipses and the 
coordinates of any of the planets at any given moment. Two centuries 
after they were compiled, these tables still contained various inaccuracies 
and were in need of revision. Toscanelli's observations of the motions of 
the sun — observations made with the help of the brass plate at the top of 
Santa Maria del Fiore — led him to correct and refine the Alfonsine 
Tables, and in doing so he put in the hands of mariners and mapmakers a 
more accurate tool for plotting their positions. 

ToscaneUi himself had a particular interest in maps and explorations. In 
1459 he interviewed a number of Portuguese sailors familiar with India and 
the west coast of Africa so that he could create a new and more accurate 
map of the world. This map then seems to have given rise, in Toscanelli's 
acute mind, to a novel and striking idea. Fifteen years later, when he was 
seventy-seven years old, he wrote to a friend in Lisbon, Fernao Martines, a 


Brunelleschi's Dome 

canon at the court of King Afonso of Portugal. He urged Martines to 
interest Afonso in a sea route to India, assuring him that the Atlantic 
Ocean was the shortest road to the spice regions of the Orient — a shorter 
road, that is, than the overland passage normally taken by merchants. Such 
a route was now necessary because parts of the overland route to India had 
been closed to Europeans after the Turks captured Constantinople in 1453. 
Toscanelli therefore appears to have been the first person in history to 
entertain the idea of sailing west in order to reach India. 

King Afonso could not be persuaded to adopt Toscanelli's plan. 
Although the nephew of Henry the Navigator, he was more interested in 
slaughtering Moors than discovering new islands in the middle of the 
ocean. But seven years later the astronomer was contacted by a relative of 
Fernao Martines: an ambitious and highly-strung Genoese sea captain 
named Christopher Columbus. An expert navigator, Columbus had sailed 
all over the known world, from Greece to Iceland to the Gold Coast of 
Africa. On his voyage to Africa he had spotted flotsam on the current — 
the trunks of pine tree, large canes, other pieces of wood — that convinced 
him of the existence to the west of further unknown lands. When he 
returned to Portugal he had seen Toscanelli's letter to Martines, which so 
inspired him that he copied it into the flyleaf of one of his books, a 
treatise on geography that would later accompany him on all four of his 
voyages to the New World. 

Toscanelli wrote back to Columbus, repeating his convictions about the 
sea route to India. He even sent Columbus a map in which the distance to 
China was optimistically calculated as being only 6,500 miles — a gross 
underestimation, of course, but a figure that gave hope to Columbus, in 
whose mind the map and the letter found fertile soil. However, Columbus 
had no better luck than Toscanelli in persuading the Portuguese to 
undertake the venture, and so in i486 he petitioned for an audience with 
representatives of King Ferdinand and Queen Isabella of Spain. The rest, 
of course, is history. Six years later, on 3 August 1492, after funds had been 
raised and promises of various honours and titles made to Columbus, the 
tiny fleet of three ships set sail from Cape Palos, near Cartagena, in the 


The Lantern 

hour before dawn. And although Columbus would later claim, with typical 
arrogance, that neither maps nor mathematics had been of any use to him, 
it is to be wondered if Europeans would have landed in the New World 
quite so early and so easily without the maps and tables that Paolo 
Toscanelli compiled with the help of his observations taken from the 
dome of Santa Maria del Fiore. 



Ingenii Viri Philippi Brunelleschi 

THE FIRST STONE of the dome's lantern was consecrated by 
Saint Antoninus, the new Archbishop of Florence, in March 1446. 
Filippo barely lived long enough to see the ceremonv% for he died 
a month later, on 15 April, after what appears to have been a short illness. 
He died in the house where he had lived for his entire life with his son and 
heir, Buggiano, at his bedside. He was sixty-nine years old and had worked 
on the site of Santa Maria del Fiore for over a quarter of a century. 

Filippo was the first of the three capomaestri to die. Battista d'Antonio 
survived him by five years. By this time Battista was comfortable and well- 
to-do, able to provide fine jewellery for his wife, a dowry for his daughter 
and a house for himself in the countr\\ He died at the end of 1451, aged 
sixty-seven, after having worked on the site of Santa Maria del Fiore for 
his entire adult life. 

Lorenzo Ghiberti was to live to the ripe old age of seventy-seven. In 
1447, a year after Filippo's death, he completed the ten scenes that make 
up his great masterpiece, the 'Doors of Paradise', though the framing and 
gilding of these bronze doors would not be finished for another five years. 
He had become a wealthy man, with vast lands and several houses, 
including a large villa in the country', and his foundr\' employed as many as 
twenty-five apprentices. When he died in December 1455 he was the most 


Ingcnii Viri Philippi BruncUeschi 

influential sculptor of his age, and it is not altogether without justification 
that he boasts in his autobiography that very few important works of art 
executed in Florence had not been devised by his hand. 

According to Vasari, the sudden death of Filippo brought tremendous 
grief to the people of Florence, who appreciated him more in death than 
they had m life. Even his enemies and rivals were said to have mourned 
him. But unlike Michelangelo, who would die before the dome of St 
Peter's was finished, Filippo had at least lived long enough to see his great 
cupola (with the exception of its lantern) brought to completion. 

Funeral obsequies were held in Santa Maria del Fiore. Surrounded by 
candles and swathed in white muslin, Filippo reposed beneath the great 
vault that he had finished building a decade earlier. Thousands of 
mourners paraded past, including the wardens of the Opera, the Wool 
consuls and masons from the cathedral. Then the candles were snuffed 
and the body was removed to the campanile, where it would remain for 
another month while a dispute ensued regarding where the capomaestro 
should be buried. This dispute suggests that Vasari exaggerates when he 
claims that even Filippo's enemies were in mourning. The delay was 
probably caused by an anti-Brunelleschi faction who did not wish to see 
him buried in style, perhaps the same men responsible for jailing him a 
dozen years earlier. Even in death Filippo was the subject of controversy.* 

His supporters eventually won the day. The Signoria decreed that 
instead of being placed inside his family's sepulchre in the newly rebuilt 
church of San Marco, where both of his parents were buried, he should 
have the honour of being entombed inside the cathedral itself, rather like a 
Pharaoh buried inside a pyramid he had spent his lifetime constructing. 
He was duly laid to rest in the cathedral on 15 May 1446. There is a fine 

* This concern for where the bones of such a distinguished citizen of Florence should be 
laid to rest prefigures how, over a century later, the corpse of Michelangelo would be 
smuggled back to Florence in a bale of wool after the great sculptor died in Rome. 
Michelangelo's saintliness is stressed by his friend Vasari, who relates the 'miracle' of how the 
corpse showed no signs of putrefaction twenty-five days after death, when it was finally 
buried in Santa Croce. 


Brunelleschi's Dome 

irony to the fact that, although Filippo did not achieve his ambition of 
building round the cathedral a series of chapels to house the bones of 
Florence's wealthiest citizens, he himself should have come to be buried 
there. This was indeed a great honour. The only other person interred 
inside the cathedral was Saint Zenobius. His ancient remains had been 
placed there only a few years earlier in a vault specially built by Filippo. 
The capomaestro was not laid to rest in a special chapel, however, but in a 
tomb under the south aisle, near to where Neri di Fioravanti's tantalising 
model had stood enshrined for so many years. So modest was this tomb 
(perhaps at the behest of his enemies) that it was only rediscovered during 
archaeological work on the cathedral in 1972. There is no grand monument 
to the capomaestro, only a simple marble tomb slab — the sort of slab that 
was cut up for use on the dome whenever marble was scarce. The 
inscription reads, 


('Here lies the body of the great ingenious man Filippo Brunelleschi of Florence.') 

It refers to him, therefore, not directly as an architect but as a man of 
mechanical genius, alluding to the machines he invented in order to raise 
the dome.* His mechanical ingenuity is also stressed in the epitaph 
composed by the Chancellor of Florence, Carlo Marsuppini, a renowned 
poet, and placed elsewhere in the cathedral. A plan was afoot shortly after 
his death to decorate the site of his tomb with marble plaques showing 
some of these machines — an exercise that would have taught us much 
about their design — but the commission, regrettably, was never carried 

In 1972 Filippo's bones were exhumed from where, for over five 
hundred years, they had lain beneath the simple tomb slab. By then the 

*The words 'genius' and 'ingenious' are etymologically related to ones that describe the 
building of machines. In medieval Latin the word for machine was ingenium, and an ingeniator 
was someone who built them, generally for military purposes. 


Ingenii Viri Philippi Brunelleschi 

skeleton had all but crumbled to dust, poignantly illustrating their stark 
contrast with the mighty vault looming overhead. Forensic tests none the 
less discovered that, true to contemporary accounts, Filippo was short in 
stature (no more than 5 feet 4 inches) even by the standards of the 
fifteenth century. He possessed, however, an above-average cranial capacity. 
We know what he looked like because shortly after his death the Opera 
commissioned from Buggiano a plaster cast of his head and shoulders. 
This bust with its closed eyes and grimacing mouth is now on display in 
the Museo dell'Opera del Duomo, where visitors can come face to face 
with the capomaestro, who looks barely larger than a child. The Opera also 
commissioned a marble bust, once again from Buggiano, who portrayed 
Filippo in the attire of an Ancient Roman. It was placed to the right of 
the cathedral's door, near to one of Arnolfo di Cambio, with whom the 
great adventure of the cathedral had begun exactly a century and a half 

These officii tributes may strike us as somewhat modest in light of all 
that Filippo accomplished, but it is safe to assume that no European 
architect or engineer had ever before earned such renown either during his 
lifetime or in the years after his death. Today we are so used to celebrating 
the brilliance of architects like Michelangelo, Andrea Palladio and Sir 
Christopher Wren that it is hard to imagine a time when architects and 
architecture were not esteemed. But the great archi tects of the Middle A ges 
h ad been virtually anonymou s. The name of the master mason who 
constructed the abbey of St Denis — the first building ever raised in the 
Gothic style — remains unrecorded, and the three masons responsible for 
the ill-fated cathedral at Beauvais are known in the documents simply as 
the First Master, the Second Master and the Third Master. A little more is 
known about Arnolfo di Cambio and Neri di Fioravanti, though history 
does not record where or when either o£ them was bom or died, nor do we 
have any indication of their personalities or aspirations. 

Part of the reason for this anonymity was a prejudice against manual 
labour on the part of both ancient and medieval authors, who assigned 


Brunelleschi's Dome 

23. Brunelleschi's death mask- 
architecture a low place in human achievement, regarding it as an 
occupation unfit for an educated man. Cicero claimed that architecture 
was a manual art on the same level as farming, tailoring and metalworking, 
while in his Moral Letters Seneca mired it in the lowest of the four categories 
of art, those which he classified as volgares et sordidae ('common and low'). 
Such arts were mere handiwork, he claimed, and had no pretence to beauty 
or honour. As such, architecture ranked even lower than the 'arts of 
amusement', which included such things as fashioning machinery for stage 

Filippo's work at Santa Maria del Fiore set architects on a different 
path and gave them a new social and intellectual esteem. Largely through 
his looming reputation, the profession was transformed during the 
Renaissance from a mechanical into a liberal art, from an art that was 
viewed as 'common and low' to one that could be regarded as a noble 


Ingenii Viri Philippi Brunelleschi 

occupation at the heart o{ the cultural endeavour. Unlike the builders of 
the Middle Ages, Filippo was far from anonymous, and his feat in raising 
the dome without a wooden centring was celebrated far and wide. Latin 
poems were composed in his honour, books were dedicated to him, 
biographies written, busts carved and portraits painted. He became the 
subject of myth. 

Above all else, Filippo was praised for his ingegno, or 'genius', a term 
invented by t he Italian humanist philosop hers to describtl A liaLifial abiliLj* 
tor original inven tion.^ Before Filippo 's time the faculty of genius was 
never attributed to architects (or to sculptors and painters either, tor that 
matter).^ But Marsuppini's epitaph refers to Filippo as possessing divino 
ingenio ('divine genius'), marking the first recorded instance of an architect 
or sculptor being said to have received divine inspiration tor his work. For 
Vasari, the capomaestro had been a genius sent from heaven to renew the 
moribund art of architecture, almost parallelling how Christ had come to 
earth to redeem mankind. Yet Filippo was neither a god nor an angel, but 
only a man, and in his unquestionable brilliance the writers of the 
Renaissance found their proof that modern man was as great as — and 
could in fact surpass — the ancients from whom they took their 


i'-- > 


The Nest of Delights 

EACH MORNING THE masons working on the dome of Santa 
Maria del Fiore arrived on the site m semi-darkness and, after 
having their names recorded on the gesso-board, started their 
labours by climbing several hundred stone steps to the workmg level. 
Their feet would rasp on the sandstone treads as they began this familiar 
but arduous ascent clutching their tools, flasks of wine and the leather 
pouches that held their lunches. Their climb through the core of the 
building was illuminated by a system of lighting that Filippo — mindful as 
ever of his workmen's safety — devised to prevent them from stumbling 
and falling in the dark stairwell. 

In all, four sets of stairs rise from the ground to the top of the tambour. 
A staircase giving access to the top of the drum, and from there into the 
dome itself, was built into each of the four enormous piers on which the 
dome rests. During construction, two of these were used for ascent and the 
other two for descent, thereby doing away with the problem of tool-laden 
masons bumping into one another in the confined spaces. The men clearly 
needed a good level of fitness to keep their jobs since by the 1430s they 
were forced to scale the equivalent of a forty-storey building before 
starting work each day. 

Originally it was feared that these four stairwells might weaken the 


The Nest of Delights 

piers, obviously a disastrous result considering that they take the bulk of 
the dome's weight, which has been estimated at 37,000 tons. In the 1380s a 
group of master masons had recommended bricking up the stairwells and 
finding another way for the labourers to reach the working levels. But these 
fears proved unfounded and, thankfully, no such work was ever done. 
Today it is therefore still possible to follow in the steps of the masons 
who scaled the heights o{ the dome. 

There are now 463 steps to the summit. Tourists begin their climb m 
the southwestern pier, passing first through the Porta dei Canonici and 
then through a much smaller door bearing an agnus dei, the emblem of the 
Wool Guild. The first 150 steps lead to the top of this pier, spiralling 
anticlockwise and thus allowing for a clockwise descent, which the 
masons, weary after a day's work, would have found less disorienting. It 
was these 150 steps that in 1418 defeated the capomaestro Giovanni 
d'Ambrogio, with whom every panting tourist can sympathise: he was 
sacked for being unable to climb them in order to inspect the 

The steps through the southwestern pier eventually lead on to an 
interior balcony that encircles the base of the dome. It was at this height 
that the masons held their small feast of bread and melons in the summer 
of 1420. From this vantage point they must have realised the magnitude of 
the task before them, because nowhere does the span of the dome seem 
greater than here, where you can gaze across the huge, echoing void. The 
vast interior of the vault that soars overhead is now decorated by one of 
the world's largest frescoes, Vasari's Last Judgement, with its gesticulating 
skeletons and gargantuan, pitchfork-wielding demons.^ Filippo anticipated 
the execution of this fresco, and iron rings from which scaffolding could 
be hung were inserted into the interior of the inner shell. The shell is also 
pierced by small windows through which a painter could crawl on to the 
hanging platform and begin work with his brushes. 

From the interior balcony a small door leads into the gradually 
narrowing space between the two shells, where another set of steps threads 
its way upwards. These steps were constructed at the same time as the 


Brunelleschi's Dome 

cupola Itself. Still remarkably unworn after more than five centuries of use, 
they were built out of sandstone beams delivered from the Trassinaia 
quarry. To the right of the staircase, sloping gently inwards, is the 
plastered surface of the inner dome, while the outer shell runs overhead in 
a parallel arc. In between these two tilting walls is a disorienting maze of 
low doorways, cramped passageways and irregularly ascending staircases 
that make the ascent a little like stepping into an Escher lithograph. It 
seems ironic that the first building built in the 'Renaissance st\4e' — this 
dome that is outwardly so ordered and graceful — should have at its core 
such a bewildering labyrinth of musty corridors. 

It is in this confusing and constricted space between the two domes that 
you can see at close hand the techniques used by Filippo and his masons. 
In the places where the plaster on the inner dome has fallen away the 
herring-bone pattern is exposed to view, its elongated bricks rubbed 
smooth as glass by many thousand passing hands. In other places the 
transverse beams of the stone chains can be seen crossing overhead like 
thick rafters. Part of the wooden chain is visible too. Its timbers are low 
enough for the present-day visitor to touch, though the original chestnut 
beams were replaced during the eighteenth century after they began to rot. 

One of the most striking features of the climb is the series of small round 
windows that pierce the outer shell like portholes. These apertures bring light 
and air into the passages of dank stone, and through them you catch brief 
glimpses of the higgledy-piggledy rooftops of Florence as they recede ever 
further below. These windows, of which there are seventy-two in all, form 
part of Filippo's method of windproofing the dome, an attempt to protect the 
structure from high winds in the same way that damage to houses from 
tornadoes can be limited by opening their doors and windows. On blustery 
days the wind can be heard whistling through their openings. 

A final set of steps (above which the outer shell has been cut back to 
allow for more headroom) leads to the octagonal viewing platform at the 
base of the lantern. It comes as a mild shock, having passed through the 
echoing, disorienting passages, then suddenly to emerge outdoors, amid 
wind and light, high above the ground, with a dizzying panorama of 


The Nest of Delights 

Florence and the surrounding hills at your feet. The buttresses of the 
lantern loom overhead like marble tree trunks, and from this proximity it 
is possible to see the immense size of their 5,000-pound blocks, as well as 
the precision with which the marble has been cut and fitted together. 
Stepping closer to the edge of the viewing platform you can see the tiled 
sides of the dome fall dramatically away. And from this spot another 
advantage of the quiuto acuto profile becomes evident: the steep rise means 
vou can see almost directly into the piazza below — and, b\' the same 
token, most of the dome, including the lantern, is visible at close range 
from the ground. 

Today tourists linger for ten or fifteen minutes on the platform before 
beginning their descent (some of them carr\^ing the cupola-shaped 
umbrellas that are sold m Florence's market stalls). Thev spend their time 
taking photographs, pointing out familiar landmarks, or even surrepti- 
tiouslv inscribing their initials on the buttresses of the lantern, which are 
now covered with graffiti. For most of them the climb is a means to an 
end, an ordeal that must be suffered m order to gain a panoramic view of 
the city. But centuries ago this long ascent was made h\ a somewhat more 
interested party. In the late 1540s, after being named architect-in-chief of St 
Peter's, Michelangelo, bv then an old man, was given three passes into the 
cupola so that he and two of his assistants could inspect Filippo's methods 
of construction before beginning work on the drum and dome of St 
Peter's. A proud Florentine, Michelangelo claimed that he could equal 
Filippo's dome but never surpass it. In fact he did not even equal it, for 
the cupola of St Peter's, completed in 1590, is almost ten feet narrower and, 
arguablv, much less graceful and striking. 

Indeed, in h eight and span the cupola of Santa Maria del Fiore has never 
really been surpassed. Sir Christopher Wren s cupola for St Paul's Cathedral 
in London, with a diameter of 112 feet, is smaller bv thirtv feet, and a more 
recent dome, that of the Capitol in Washington DC, is only 95 feet in span, 
less than two-thirds the size of the one in Florence. Not until the twentieth 
centur\' were wider vaults raised, and then only by using modern materials like 
plastic, high-carbon steel and aluminum, which have permitted the 


Brunelleschi's Dome 

construction of vast tent-like structures such as the Astrodome in Houston, 
Texas, or the lightweight, prefabricated geodesic domes of Buckminster 
Fuller. Even so, it is no coincidence that, like Michelangelo, the master o{ 
large-scale concrete vaulting in the twentieth century, Pier Luigi Nervi, made 
a technical examination of Santa Maria del Fiore in the 1930s before 
developing the vaulting techniques he used in structures such as the Vatican 
audience hall and the Palazzo dello Sport m Rome. It seems wholly 
appropriate that this masterpiece executed by Filippo, the 'treasure hunter' 
who once surveyed the ruins of Rome, should have become an object of study 
by the generations of architects who followed him. 

The effect of the dome has been eloquently described bv Alberti in Delia 
tranquillita deWanimo, his dialogue on the tranquillity^ of the soul. Here he has 
the disillusioned politician Agnolo Pandolfini — the man who finds solace 
for his troubled mind in fantasies about gigantic hoists and cranes — 
compare the state of spiritual calm to the peaceful interior of Santa Maria 
del Fiore, through which he strolls with his companion Nicola de' Medici, 
the failed banker. For Agnolo, the cathedral is an example of grace under 
pressure, of an ability to withstand the blows of fortune that he compares 
to adverse weather conditions that buffet the walls of the building but 
leave the beautiful interior pacific and unruffled: 

Within, one breathes the perpetual freshness of spring. Outside there may be frost, fog or 
wind, but in this retreat, closed to every wind, the air is quiet and mild. What a 
pleasant refuge from the hot blasts of summer and autumn! And f it is true that delight 
resides where our senses receive all that they can demand of nature, how can one hestitate 
to call this temple a nest of delights? 

Yet, for all its grandeur, the cathedral and its dome have not been as 
impervious to the elements and other outside forces as Agnolo suggests. 
Vasari was to claim that the heavens themselves are envious of the dome 
since every day it is struck by lightning, and over the years a number of 
these strikes have caused serious damage. No means of countering 


The Nest of Delights 

lightning existed at the time, and a system of lightnmg rods was not 
introduced at the cathedral until the second half of the nineteenth century, 
bv which time the lantern had needed major repairs on several occasions.* 
The most dramatic of these blows fell on 5 April 1492, when a lightning 
bolt sent several tons of marble cascading into the streets on the north side 
of the cupola, in the direction of the Villa Careggi, which stands in the 
hills above Florence. The Villa Careggi was the countr\' home of Lorenzo 
de' Medici, the grandson of Cosimo de' Medici and, like Cosimo, the ruler 
of Florence and a generous patron of the arts. To Lorenzo, lying ill with a 
fever in the villa, the meaning of the destructive strike was unmistakable: 'I 
am a dead man!' he exclaimed upon being told in which direction the 
rubble had fallen. Lorenzo's physicians attempted to avert this fate, feeding 
him potions made from pulverised diamonds and pearls, and cautioning 
him to avoid both grape pips and the air at sunset, two things considered 
fatal to a man in his condition. But thev laboured in vain, and true to his 
prediction Lorenzo died three davs later, on Passion Sunday. 

In 1639 a series of cracks appeared on the interior of the inner shell. These 
are similar to those that appeared at almost the same time m the dome of St 
Peter's. They run vertically from the oculus to the drum, cutting through 
Vasari's fresco and in many places following the line of the herring-bone 
bond. The causes of these fissures, as well as the remedial measures they call 
for, have been matters of debate ever since. Sophisticated thermal measuring 
devices have been inserted into a series of holes bored in the inner dome in 
order to monitor the cracks, and in 1970 Rowland Mainstone suggested as 
their probable cause the expansion of the iron rods in the iron-and-sandstone 
chains. This increase in size was the result, he claimed, of both temperature 
changes and the penetration of the masonry' by moisture which was causing 
the iron to rust. He found that the cracks were not, like those in the dome of 
St Peter's, the result of an inherent structural deficiency given that the 

* The Ancient Romans had a dubious method of protecting their buildings from lightning 
beheving that eagles and sea-calves were never struck, they buried the corpses of these 
creatures withm the walls in the hope of warding off disaster. 


Brunelleschi's Dome 

|s:iran.x;y»>-g«-*' • 









^, /^ '\^* ,i. 

24. & 25. The lantern being struck by lightning in 1601 — and 
the scaffolding erected to repair it. 

materials used were able to withstand the stresses generated by the cupola.'^ 
Another cause might be the cathedral's alarmingly poor foundations: in the 
1970s a hydrologist discovered that a subterranean stream flows under the 
southwest corner of the dome, directly beneath the pier in whose staircase 
tourists now begin their ascent. The massive cupola was raised, in other 
words, on top of an underground river. 

Shortly after Mainstone's analysis, a commission appointed by the 
Italian government reported, to widespread alarm, that the cracks in the 
dome were growing in both length and breadth. This claim had been 
dramatically illustrated a few months earlier by the fall of a large fragment 
of Vasan's fresco. The worsening situation was blamed on a violent form 
o^ stress that Filippo, for all his genius, could not have anticipated: heavy 
traffic. Cars and buses were immediately banned from the area around the 
cathedral, and today only refuse lorries on their early-morning rounds are 
permitted to trundle through the Piazza del Duomo. Filippo's dome, so 


The Nest of Delights 

long impervious to the harsh vagaries of the weather, is now also safe from 
the scourge of the motor car. 

Today, as for the past five centuries, the mountainous form of the cupola 
dominates Florence. It looms above the narrow streets as you walk them, 
or breaks unexpectedly into view whenever you turn a corner or enter a 
piazza. It can be seen from the steps of churches such as San Miniato al 
Monte, from hotel balconies (as Lucy Honeychurch discovers m E. M. 
Forster's A Room With a F/^w) and from the terraces of cafes. On clear days 
it is even visible from as far away as Pistoia, fifteen miles to the west, 
where in the fifteenth century the citizens renamed one of their streets 
the Via deU'Apparenza, the 'Street of the Appearance', as if the dome 
were not simply brick, stone and marble, the result of a remarkable feat 
of structural engineering, but instead a miraculous apparition, the 
handiwork of God or his angels that had materialised overnight in the 
Arno Valley like the fresco in the convent of Santissima Annunziata that 
the Florentines believed was painted by an angel. And there is indeed 
something miraculous about the sight of the dome regardless of where it is 
viewed from, whether close up or far away. The fact that it was built by 
men — and built amid war and intrigue, with only a limited understanding 
of the forces of nature — only makes it more of a wonder. 



1 See Franklin K. B. Toker, 'Florence Cathedral: The Design Stage', Art Bulletin 60 
(1978), pp. 226-7. 

2 Although the precise details of his role in the design of the cupola are not i 
known for certain, Neri is constantly identified in the documents as the leader I 
of the committee: the 1367 project is defined 3iS facto per Nerium Tioravantis et alios ■ 
magistros et pictores ('done by Neri di Fioravanti and other masters and painters'). 
Other members of the committee included Taddeo Gaddi, formerly one of 
Giotto's assistants; Andrea Orcagna, a pupil of Andrea Pisano and the most 
pre-eminent artist in Florence following the death of Giotto; and Orcagna's 
brother, Benci di Gione. 

3 Much later the Spanish architect Antonio Gaudi would refer to the flying 
buttresses of Gothic cathedrals as unfortunate 'crutches'. He sought to design 
structures that would channel the lateral thrusts to the ground more directly. 
See Jack Zunz, 'Working on the Edge: The Engineer's Dilemma', in 
R. J. W. Milne, ed.. Structural Engineering: History and Development (London: E. & 
F. N. Spon, 1997), p. 62. 

4 The exact dating of the plan for the tambour is difficult to determine, as is its 
original designer. Giorgio Vasari, not always reliable, attributes its design to 
Brunelleschi: see Lives of the Artists, 2 vols, ed. and trans. George Bull 
(Harmondsworth, Middlesex: Penguin, 1987), vol. i, p. 141. This argument is 
accepted in Carlo Guasti, La cupola di Santa Maria del Fiore (Florence, 1857), pp. 
189—90, and Frank D. Prager and Gustina Scaglia, Brunelleschi: Studies of his 
Technology and Inventions (Cambridge, Mass.: MIT Press, 1971) pp. 18—22. Other 
scholars date the plans for the project much earlier, attributing them variously 
to Arnolfo di Cambio, Giovanni di Lapo Ghini, or Andrea Orcagna. See A. 
Nardini-Despotti-Mospignotti, Filippo Brunelleschi e la cupola (Florence, 1885), p. 
97; E. von Stegmann and H. von Geymtiller, Die Architektur der Renaissance in der 
Toskana (Munich, 1885—93), pp. 38ff; and Howard Saalman, Filippo Brunelleschi: The 
Cupola of Santa Maria del Fiore (London: A. Zwemmer, 1980), p. 48. 

5 The dome of San Vitale in Ravenna, built in the sixth centur\' AD, consists of a 
double shell. Closer to home, the Baptistery of San Giovanni in Florence is 



technically a double dome in that it features an octagonal vault surmounted by 
a pyramidal wooden roof. It is usually assumed that the Baptistery is the 
prototype for the dome of Santa Maria del Fiore. After the cupola of Santa 
Maria del Fiore was built, it would become a standard feature of domes in 
Europe, including St Peter's in Rome. Sir Christopher Wren's design for St 
Paul's in London would even call for three domes, one inside the other. 


1 For Brunelleschi's career as a clockmaker, see Frank D. Prager, 'Brunelleschi's 
Clock?' Physis 10 (1963), pp. 203—16. 

2 A point made by Frederick Hartt in 'Art and Freedom in Quattrocento 
Florence', in Essays in Memory of Karl Lehmann, ed. Lucy Freeman Sandler (New 
York: Institute of Fine Arts, 1964), p. 124. 

3 See Richard Krautheimer, Lorenzo Ghiherti (Prmceton: Princeton University 
Press, 1956), p. 3. 


1 For the classic statement of this connection, see Hans Baron, The Crisis of the 
Early Italian Renaissance: Civic Humanism and Repuhlican Liberty in an Age of Classicism 
and Tyranny (Princeton: Princeton University Press, 1955). 

2 This ordinance had ordered Florence's merchants to employ the more 
cumbersome Roman numerals instead of Arabic ones, whose shapes had not 
yet been standardised, therefore giving rise, potentially, to confusion and error. 
Resistance to Arabic notation was common in Europe during the Middle Ages. 
See David M. Burton, Burtons Liistory of Mathematics (Dubuque, Iowa: William C. 
Brown, 1995), p. 255. 

3 Filippo's reputation as the revivalist of Roman architecture — a reputation 
established by Manetti and Vasari — has lately come under scrutiny from a 
number of scholars who argue that his architectural vocabulary (pediments, 
semicircular arches, fluted pilasters, Corinthian capitals) could actually have 
been acquired much closer to home, and from buildings of a more recent date. 
See, for example, Howard Saalman, 'Filippo BruncUeschi: Capital Studies', Art 
Bulletin 40 (1959), pp. iisff; Howard Burns, 'Quattrocento Architecture and the 
Antique: Some Problems', in R. R. Bolgar, ed.. Classical Influences on European 
Culture (Cambridge: Cambridge University Press, 1971), pp. 269—87; and John 


Brunelleschi's Dome 

Onians, Bearers of Meaning: The Classical Orders in Antiquity, the Middle Ages and the 
Renaissance (Cambridge: Cambridge University Press, 1988), pp. 130-6. Onians 
argues, for instance, that Filippo participated in a 'Tuscan Renaissance' as 
opposed to a Roman one: Filippo saw his task 'as essentially to purifv and 
regularise the primitive Tuscan architecture which was best represented in the 
Baptister\'' (p. 136). Onians even dismisses Filippo's visit to Rome as an 
invention of Manetti. But for evidence of this sojourn, see Diane Finiello 
Zervas, Tilippo Brunelleschi's Political Career', Burlington Magazine 121 (October 
1979), p. 633. A case for Filippo's study of Roman remains — particularly their 
structural details — is also made by Rowland Mainstone. See 'Brunelleschi's 
Dome of S. Maria del Fiore and some Related Structures', Transactions of the 
Newcomen Society 42 (1969—70), p. 123; and 'Brunelleschi's Dome', Architectural 
Review (September 1977), pp. 164—6. 


1 See Martin Kemp, 'Science, Non-science and Nonsense: The Interpretation oi 
Brunelleschi's Perspective', Art History (June 1978), pp. 143—5; ^^^ Jehane R. 
Kuhn, 'Measured Appearances: Documentation and Design in Early Perspective 
Drawing', Journal of the Warburg and Courtauld Institutes 53 (1990), pp. 114—32. 

2 Rowland Mainstone, 'Brunelleschi's Dome', p. 159. 

3 See, for example, J. Durm, 'Die Domkuppel in Florenz und die Kuppel der 
Peterskirche in Rom', Zeitschrift fur Bawwesen (Berlin, 1887), pp. 353—74; Stegmann 
and Geymiiller, Die Architektur der Renaissance in der Toskana (Munich, 1885—93); 
and Paolo Sanpaolesi, La cupola di Santa Maria del Tiore (Rome: Reale Istituto 
d'Archaologia e Storia dell' Arte, 1941). 


1 It has been suggested that Lorenzo, like Filippo, proposed to vault the cupola 
without armature. See Paolo Sanpaolesi, 'II concorso del 1418—20 per la cupole 
di S. Maria del Fiore', Rivista d'arte (1936), p. 330. But no evidence supports this 
claim. See Krautheimcr, Lorenzo Ghiberti, p. 254. 

2 The Barbadori Chapel was endowed by Bartolomeo Barbadori, a wealthy wool 
merchant who died of the plague in 1400. His son Tommaso was serving the 
Opera del Duomo in 1418. The Ridolfi Chapel was endowed by Schiatta 
Ridolfi, one of the Wool consuls in 1418. 



3 Marvin Trachtenberg, 'Review of Howard Saalman, Filippo Brunelleschi' , Journal of 
the Society of Architectural Historians 42 (1983), p. 292. 

4 For the argument in favour of Filippo's authorship, see Saalman, Filippo 
Brunelleschi, pp. 77—9. 


1 Sanpaolesi, La cupola di Santa Maria del Fiore, p. 21. 

2 Vincent Cronm, The Florentine Renaissance (London: CoUms, 1967), p. 96. 

3 William Barclay Parsons, Engineers and Engineering in the Renaissance (Baltimore: 
Williams & Wilkins, 1939), p. 589. 


1 These dimensions have been calculated m Frank D. Prager, 'Brunelleschi's 
Inventions and the "Renewal of Roman Masonry Work'", Osiris 9 (1950), p. 


2 Prager, 'Brunelleschi's Inventions', p. 524. 

3 Prager, 'Brunelleschi's Inventions', p. 517. 

4 Prager and Scaglia, Brunelleschi: Studies of his Technology and Inventions, p. 80. 

5 See Paul Lawrence Rose, The Italian Renaissance of Mathematics: Studies in Humanists 
and Mathematicians from Petrarch to Galileo (Geneva: Librairie Droz, 1975). 

6 On the possible design of Filippo's clock, see Prager, 'Brunelleschi's Clock?', 
pp. 203—16. 


1 Hugh Plommer, ed., Vitruvius and Later Roman Building Manuals (Cambridge: 
Cambridge University' Press, 1973), p. 53. 

2 John Fitchen notes that many Byzantine churches besides Santa Sophia 
incorporated wooden ties to reduce the impact of earthquakes. See The 
Construction of Gothic Cathedrals: A Study of Medieval Vault Erection (Oxford: Oxford 
University Press, 1961), p. 278. 

3 Mainstone, 'Brunelleschi's Dome of S. Maria del Fiore*, p. 116. 


I The story is prmted m Thomas Roscoe, ed., The Italian Novelists, 4 vols 
(London, 1827), vol. 3, pp. 305—24. 


Brunelleschi's Dome 


1 The only source for this stor\' — not related by either Manetti or Vasari — is 
Giovanni Battista Gelli's account in Brevi vite di artisti Jiorentini, published during 
the sixteenth century. 

2 Dumas, ed., A History of Technology and Invention (London: John Murray, 1980), p. 


3 Eugenio Battisti, Brunelleschi: The Complete Work, trans. Robert Erich Wolf 
(London: Thames & Hudson, 1981), p. 361. Several scholars have proposed a 
different method of curvature control, the so-called gualandrino con tre corde 
mentioned in the 1426 amendments to the cupola programme. This procedure 
involves a complicated series of triangulations performed with three ropes 
stretched across the diameter of the cupola. For reconstructions, see Mainstone, 
'Brunelleschi's Dome', p. 164, and Saalman, Filippo Brunelleschi, pp. 162—4. ^" ^^^^> 
however, the gualandrino was not a system of curvature control but a safety 
harness worn by the masons: see Battisti, p. 361. 

4 See Howard Saalman, 'Giovanni di Gherardo da Prato's Designs concerning the 
Cupola of Santa Maria del Fiore in Florence', Journal of the Society of Architectural 
Historians 18 (1950), p. 18. 


1 For information on the brick-making industry in Florence, I am indebted to 
Richard A. Goldthwaite, The Building of Renaissance Florence: An Economic and Social 
History (Baltimore: The Johns Hopkins University Press, 1980), pp. 171— 212. 

2 Saalman, Filippo Brunelleschi, p. 199. 

3 Mainstone, 'Brunelleschi's Dome of Santa Maria del Fiore and some Related 
Structures', p. 114. Mainstone calculates that at this pace there would be 'ample 
time for each course to become self-supporting before the next was added' (pp. 

4 Samuel Kline Cohn, Jr., The Laboring Classes in Renaissance Florence (New York: 
Academic Press, 1980), p. 205. 

5 Lives of the Artists, vol. i, p. 156. 

6 Mainstone, 'Brunelleschi's Dome of S. Maria del Fiore', p. 113. 

7 See Robert Field, Geometrical Patterns from Tiles and Brickwork (Diss, Norfolk: 
Tarquin, 1996), pp. 14, 40; and Andrew Plumbridge and Wim Meulenkamp, 
Brickwork: Architecture and Design (London: Studio Vista, 1993), pp. 146—7. 



8 See Iris Origo, 'The Domestic Enemy: The Eastern Slaves in Tuscany in the 
Fourteenth and Fifteenth Centuries', Speculum: A Journal of Mediaeval Studies 30 
(July 1955), pp. 321-56. 


1 See Christine Smith, A rchitecture in tf^e Culture of Farley f-f^pianism: Ethics, Aesthetics a nd 
Eloquen ce, l^oo —l^yo (Oxford: Oxford Univers ity Press, 1992), pp. 40—53. 

2 This point is made in Smith, Architecture in the Culture of Early Humanism, p. 45. 

3 Mainstone, 'Brunelleschi's Dome', p. 163. 

4 Mainstone, 'Brunelleschi's Dome', p. 164. 

5 See Karl Lehmann, 'The Dome of F^eaven', Art Bulletin 27 (1945), pp. 1—27; and 
Abbas Daneshvari, Medieval Tomb Towers of Iran: An Iconographical Study (Lexington, 
Kentucky: Mazda Publishers, 1986), pp. 14—16. 


1 M. E. Mallett, Florentine Galleys of the Ffteenth Century (Oxford: Clarendon Press, 
1967), p. 16. 

2 See Maximilian Frumkin, 'Early History of Patents for Invention', Transactions of 
the Newcomen Society 26 (1947—9), p. 48. 

3 Quoted in Prager and Scaglia, Brunelkschi, p. iii. 

4 Quoted m Prager and Scaglia, Brunelkschi, p. 129. 


1 Prager and Scalia, Brunelkschi, p. 131. 

2 Quoted in Prager and Scaglia, Brunelkschi, p. 129 


1 Goldthwaite, The Building of Renaissance Florence, p. 257. 

2 See Zervas, 'Filippo Brunelleschi's Political Career', pp. 630—9. 

3 Battisti, Filippo Brunelkschi, p. 42. 


Brunelleschi's Dome 


1 Ad Luciliurn Epistulae Morales, 3 vols, trans. Richard M. Gummere (London: 
Heinemann, 1920), vol. 2, p. 363. 

2 See Christine Smith, Architecture in the Culture of Early Humanism, p. 30; and Martm 
Kemp, 'From Mimesis to Fantasia: The Quattrocento Vocabulary of Creation, 
Inspiration and Genius in the Visual Arts', Viator 8 (1977), p. 394, 

3 For a discussion, see Kemp, 'From Mimesis to Fantasia , pp. 347—98, 


1 The details of this system of lighting are not recorded, unfortunately, and so 
remain a matter o{ conjecture. But alchemists of the day — inspired bv stories 
from the Roman histories about how a perpetual fire was kindled in the 
Temple of \^esta in Rome — were interested in flames that would burn 
continuously. Accordingly, thev conducted experiments in which, for example, 
salt was added to lamp oil to make it burn more slowly. Other experiments — 
equally unsuccessful — saw wicks made from 'incombustible' stones. For a 
discussion of these experiments, see Giovanni Battista della Porta, Natural Magick 
in XX Books (London, 1658), p. 303. 

2 Paolo Galluzzi, Mechanical Marvels: Invention in the Age of Leonardo (Florence: Giunti, 
1996), p. 20. 

3 The fresco was begun by Vasari in 1572 and completed after his death by 
Federico Zuccaro (1540— 1609). It was restored between 1981 and 1994. 

4 Mainstone, 'Brunelleschi's Dome of S. Maria del Fiore and Some Related 
Structures', pp. 120— i. In 1743 three iron rings needed to be installed in St 
Peter's in order to prevent the cracked dome from collapsing altogether. The 
incorporation of these chains is a landmark in the history of structural 
engineering. Three French mathematicians — Boscovitch, le Seur and Jacquier — 
calculated the horizontal thrust of the dome as well as the tensile strength of 
iron and the resistance of the drum walls. Their work represents the first time 
that statics and structural mechanics were successfully applied to such a 
problem. For discussions, see Hans Straub, A History of Civil Engineering, trans. 
E. Rockwell (London: L. Hill, 1952), pp. 112— 16; and Edoardo Benvenuto, An 
Introduction to the History of Structural Mechanics, 2 vols (New York: Springer- 
Verlag, 1991), vol. 2, p. 352. 


Select Bibliography 

Albert!, Leon Battista, Ten Books on Architecture (London: A. Tiranti, 1965) 
Battisti, Eugenio, Brunelleschi: The Complete Work (London: Thames & Hudson, 1981) 
Gaertner, Peter, Brunelleschi (Cologne: Konemann, 1998) 
Galluzzi, Paolo, Mechanical Marveb: Invention in the Age of Leonardo (Florence: Giunti, 

Ghiberti, Lorenzo, The Commentaries, trans. Julius von Schlosser (London: 

Courtauld Institute of Art, 1948—67) 
Goldthwaite, Richard A., The Building of Renaissance Tlorence: An Economic and Social 

History (Baltimore: Johns Hopkins University Press, 1980) 
Mainstone, Rowland J., 'Brunelleschi's Dome' Architectural Review (September 

i977)» 157-66 
Mainstone, Rovv^land J., 'Brunelleschi's Dome of S. Maria del Fiore and Some 

Related Structures' Transactions of the Newcomen Society 42 (1969—70), 107—26 
Mainstone, Rowland J., Developments in Structural Torm (Cambridge, Mass.: Harvard 

University Press, 1975) 
Manetti, Antonio di Tucci, The Life of Brvinelleschi, trans. Catherine Enggass 

(University Park: Pennsylvania State University Press, 1970) 
Prager, Frank D., 'Brunelleschi's Clock?' Physis 10 (1963), 203—16 
Prager, Frank D., 'Brunelleschi's Inventions and the "Renewal of Roman 

Masonry Work'" Osiris 9 (1950), 457—554 
Prager, Frank D. and Gustina Scaglia, Brunelleschi: Studies of his Technology and 

Inventions (Cambridge, Mass.: The MIT Press, 1970) 
Saalman, Howard, Tilippo Brunelleschi: The Cupola of Santa Maria del Tiore (London: 

A. Zwemmer, 1980) 
Toker, Franklin K. B., 'Florence Cathedral: The Design Stage' Art Bulletin 60 

(1978), 214-30 
Vasari, Giorgio, Lives of the Artists, 2 vols, ed. and trans. George Bull 

(Harmondsworth, Middlesex: Penguin, 1987) 




Acqua Claudia, Rome, 24 
Aeschylus, 65 

Afonso, King of Portugal, 152 
Alberti, Leon Battista, 32, 38, 94, 95, 

103-4, 105. "9' 137 
On Architecture, 100 
On Painting (De pictura), 65/7, 137 
On the Tranquillity of the Soul, 58, 164 

Albertini, Francisco, 19 

Albizzi, Rinaldo, 134 

Alexander of Aphrodisia, 43 

Alfonsine Tables, 151 

Alfonso, King of Naples, 32 

Antoninus, St, Archbishop of Florence, 

Antonio da Vercelli, 68 
Antonio di Banco, 37, 39 
Antonio di Battista, 135 
Apollo Belvedere, in 
aqueducts, Roman, 24, 83, 103 
arch construction, 27, 87—8 

wooden centring, j6, 38—40, 41—2, 47, 

49, 55, 92, 96, 120 
architects, 6—7, 47—8, 157—9 

see capomaestri 
Arno, River, 2, 73, 113 

transportation, 3, in, 113— 14, see 

Badalone, II 
Arnolfo di Cambio, 4, 6, 124, 157 
Arte dei Maestri di Pietra e di Legname, 

see Masons Guild 
Astrodome, Houston, Texas, 164 

astrolabes, 104, 150— i 
astronomy, 149—51 
Aurispa, Giovanni, 65 

Babel, Tower of, 102—3 
Bacon, Roger, 25—6 
Badalone, II, 114— 19, 127 
Baptistery of San Giovanni, Florence, 4, 
14, ij, zz, 36-7, J7, 168-9 ("5) 
bronze doors, 14, 15, 17—20, 44, 143, 


Barbadori Chapel, Santa Felicita, 
Florence, 46—7, 121 

Bargello, Florence, 7 

Battista d'Antonio, 47—8, 52, 119, 135, 154 

Beauvais, France: Cathedral of Saint- 
Pierre, 8, 9—10, 157 

Benci di Cione, 168 (n2) 

Bernard of Clairvaux, 103 

Bernardino of Siena, 129 

Biagio d'Antonio: Archangels in a Tuscan 
Landscape, 105 

hianchi marmi (marble), 110— 11, 112, 146, 

Black Death, 4, 14, 17, 18, 23, 89 

Boccaccio, Giovanni, 34 
Decameron, 33—4 


bell tower (campanile), 8 
San Petronio, 7 

hraccia, Florentine, 6 

Bracciolini, Poggio, 83 


Brunelleschi's Dome 

brickmaking, Florentine, 93 
brickwork (of cupola), 92—4, 96, 96, 
98—101, 105—7, 108, 162 
measurement of curvature, 84—7 
mortar, 94—6 
bronze casting, 17—18 
brothels, 129 
Brunelleschi, Filippo: 
appearance, 33, 157 
apprenticeship, 12—13 
Baptistery doors competition, 14—15, 

17, 18, 19—20 
Barbadori and Ridolfi chapels, 46—7, 

86, 121 
becomes capomaestro, 48 
and Cavalcanti ('II Buggiano'), 46, 

character and personality, 19, zo, 80, 

117— 18, 136, 145, 159 
death, 154, 155—7 
death mask, 157, ij8 
education, 65, 107, 109, 117 
and Ghiberti, 18, 20, 48, 68, 77, 

78—80, 89—90 
and Giovanni da Prato, 49, 87—91, 

imprisonment, 131, 132—4 
inventions and experiments: 
// Badalone, 114— 19, 127 
clocks, 13, 66, 67 
crane (^castello), 68—9, 70, 71, 75 
lantern crane, 148 
lantern hoist, 145—6, /^y 
Lucca dam, 125—9 
ox-hoist, 59—60, 6/, 62—7, 6j 
perspective, 35—7, J 7 
military commissions, 124—5 
model for dome, 37—8, 40—3, 46, 

49-50, 54-6 
proposals for chapels, 121, 122, 130, 131 

m Rome, 10, 23, 24—7, 31—2, 36, 104 

salary and prizes, 34, 48, 49, 66, 91, 
119, 130, 136, 146 

secret codes, 19, 25—6, 146 

'The Tale of the Fat Carpenter', 80—2 

and Toscanelli, 149 

see also brickwork; lantern; sandstone 
chains; wooden chain 
Brunellesco di Lippo Lappi, Ser, 12, 135 
Bn.mi, Leonardo, 22 
Buggiano, nr Pistoia, 135 
Buggiano, II, see Cavalcanti, Andrea 
Buonaccorso, Cione, 18 
buttresses, flying, 7 

Caesar, Julius, 14, iz 

'Caesar Alphabet', 146 

Callias, 56/1 

Campanile, Florence, 3, iii 

Campiglia, 148 

Capitol, Washington DC, 163 

capomaestri, 6, 47—8; see also Battista 

d'Antonio; Brunelleschi, Filippo; 

Giovanni d'Ambrogio; Giovanni 

di Lapo Ghini 
Capponi, Neri, 127 
Carrara marble, iii— 13, 148 
Castellina in Chianti, 16 
castello (crane), 68—9, 70, 71, 75 
Catullus, 32 
Cavalcanti, Andrea ('II Buggiano'), 46, 

134-8, 154, 157 
Celer (architect), 28 
centring, see arch construction 
Charles VIII, King of France, 36 
chiaroscuro, 36 

Chronica de origine civitatis, zz 
Cicero, 32, 158 
Cimabue, 33 
Ciompi uprising, 97—8 




ciphers, see codes, secret 
clocks, 13, 53, 66, 67 
Cloth Merchants Guild, 14, 17, 44 
codes, secret/ciphers, 19, 25—6, 146 
Cologne Cathedral, Germany, 30 
Colosseum, Rome, 27 
Columbus, Christopher, 152—3 
concrete, Roman, 27, 28, 30 
Constance, Council of, 45 
Constantinople, 152 

Santa Sophia, 6, 76 
Corinthian order, 26, 27 
cracks, 45, 121, 165—7 
craftsmen, see workmen 
cranes and hoists: 

castello, 68—9, 70, 71, 75 

lantern crane, 148 

lantern hoist, 145—6, l^y, 148 

ox-hoist, 59—60, 61, 62—7, 6^ 

rota magna, 59—60, 120 

Stella, 67—8 

Dante Alighieri, 34, 48 

Convivio, 22 

Divine Comedy 107, 109, lO^ 
deaths and mjuries, 54, 97 
Demosthenes, 65 
Diocletian, Emperor, 52 
diving operations, 119 
Domenico da Prato, 35 
Domenico di Benintendi, 126 
Domitian, Emperor, 103 
Domus Aurea (Golden House), Rome, 

Donatello, 13, 24—5, 34, 40, 41, 81, 130, 

136, 137 
Donato di Valentmo, 54 
Dondi, Giovanni de', 26 
Doric order, 26, 27 

earthquakes, 23, 24, 76—7, 122 
Eiffel, Gustave, 149 
Eugenius IV, Pope, 137, 139—41 
executions, 134 

Faventinus, 74 

feast days, 52, 139—40 

Fibonacci, Leonardo: Practica geometriae, 26 

Fiesole, 14 

see also Trassinaia quarry 
Fiesole, Bishop of, 141 
Filarete, Antonio, 32, 141^ 
Florence, 2—3 

democracy, 16 

foundation, 22—3 

plague, 4, 14, 17, 18 

population, 2, 4 

quarries, 2, 73 

Roman remains, 22 

Santa Croce district, 13 

walls, 3, 124 

war with Lucca, 122, 123—4, i25~9» ^'^' 

war with Milan, 16—17, ^o— i 

see also Arno, River 
flying buttresses, 7 
Forli, 123 
Tour Officials of the Cupola', 47, 48, 

Francesco di Giorgio, 32, 119 

sketch of boat with paddle wheels, 
Frediano, St, 125—6 
freemasons, 48?! 
Frontinus, Sextus Julius, 103 

On Aqueducts, 83 
Fuller, Richard Buckminster: geodesic 

dome, 164 
funerals, 54 


Brunelleschi's Dome 

Gaddi, Taddeo, i68 (mz) 

Galileo Galilei, i6n, 43, 149 

Genoa, 119, 123, 124 

geodesic domes, 164 

Ghiberti, Bartolucci, 18, 19, 44, 135 

Ghiberti, Buonaccorso: 

sketch of lantern hoist, 146, /^y 
sketch of turnbuckles and lewis bolt, 

Ghiberti, Lorenzo: 
appearance, 18, 44 
apprenticeship, 135 
Baptistery doors, 18—20, 143, 154 
and Brunelleschi, 18, 10, 48, 68, 77, 

78—80, 89—90 
Commentarii (autobiography), zo 
joins Masons Guild, 133 
models submitted, 43, 45, 144 
St John the Baptist, Orsanmichele, 


Santa Maria Novella staircase, 46 
Giza: Great Pyramid, 30 
Giotto, 33, 36, 47, 124, 132 

Campanile, Florence, 3, in 
Giovanna, Queen of Naples, 137 
Giovanni d'Ambrogio, 37, 45, 161 
Giovanni da Prato, 48—9, 78, 80, 87, 

88—91, 116, 117, 118, 119, 144 
Giovanni di Lapo Ghini, 6, 8, 65 

model for dome, 6, 7, 40 
goldsmiths, 12—13, '9 
Gothic architecture, 7, 9, 10, 16, 84—5, 

87, 90, 103, 157 
Gozzoli, Benozzo, 13 
Great Schism (papacy), 45 
guilds, 131— 2 

Cloth Merchants, 14, 17, 44 

Masons, 54, 93, 131— 2, 133 

Silk Merchants, 46, 133, 135 

Wool Merchants, 6, 41, 46, 47, 161 

Guinigi, Paolo, 124 
gunpowder, 125 

Hawkwood, Sir John, 123 

Henrv', Prince ('the Navigator'), 150 

Hiram of Tyre, 48^ 

hoists, see cranes and hoists 

holidays, 52, 139—40 

homosexuals, 129 

Hooke, Robert, i6n 

hoop stress, 30, 31, j/ 

hydraulic engineering schemes, 126—7 

Ionic order, 26, 27 
Islamic architecture, 10, 100 

Jacopo di Niccolo, 72 
John the Baptist, St: relics, 141 and n 
John XXIII, antipope, 45, 141M 
Justinian, Emperor, 6 

Kepler, Johann, z6n 
Kimon of KJeonai, 35 

labour force, see workmen 
lantern (on dome), 141, 143—9, 154 

lightning strikes, 165, /66 

sphere, 71, 141, 145 
Laocoon, 28 
Lapi, Apollonio, 35 
Lastra a Signa, 16 
lead poisoning, 74 

Leonardo da Vinci, 13, 25, 34, 59, 71, 114, 

drawing of castello, yo 
lewis bolts, 63, 69 
lighting (in dome), 49, 90-1, 160 
lightning strikes, 164—5, 166 
limestone, 73, 74 
Livy, 32 





St Paul's Cathedral, 163, 169 («5) 

Westminster Abbey, 23, 97 

Westminster Hall, 85 
Lotti, Benincasa, 12—13 
Lucca, campaign agamst, 122, 123—4, 

125-9, 13O' 133 
Lucretius, 32 

Machiavelli, Niccolo: Storie fiorentine, 128 

macigno, 72—3 

Mainstone, Rowland, 106, 165 

Malmantile, 16, 124—5 

Manetti, Antonio di Ciaccheri, 144, 145, 

Manetti, Antonio di Tuccio: Life of 

Brunelleschi, 20, 25, 26, 34, 36, 41, 
42, 65, 66, 76, 80, 86, 94, 97, 
137, 144 
Manetto di Jacopo, 80—2, 134 
manuscripts, Greek and Roman, 32, 65 
marble no— 11, 115, 141, 146, 148 
extraction and working, iii— 12 
transportation, in, 112— 13 
marmum rubeum (marble), no 
Marsuppini, Carlo: epitaph to 

Brunelleschi, 156, 159 
Martin V, Pope, 45—6 
Martines, Fernao, 151— 2 
Masaccio, 34, 136 
Masons Guild, 54, 93, 131— 2, 133 

see also stonemasons 
measuring devices, 84, 85—7 
Medici family, 121 

Cosimo de' Medici, 133, 134, 135, 139, 

Giovanni di Bicci de', 15, 46, 133, 135 
Lorenzo de' ('the Magnificent'), 36, 

Nicola de', 58, 164 

Memphis, Egypt, 126 
Mercanzia, prison of the, 134 
Michelangelo Buonarroti, 18, 32, 34, 72, 
III, 124, i55n 
St Peter's, Rome, 90, 155, 163 

Cathedral, 16, 88 

Dukes, see Visconti, Giangaleazzo; 
Visconti, Filippo Maria 
Milo, ruler of Croton, 126 
Mirabilia urhis romae (guidebook), 23—4 
models, architectural, 1—2, 3, 6—7, 56 
see also Brunelleschi, Filippo; Giovanni 
di Lapo Ghini; Neri di 
mortar, 94—6 

Nanni di Banco, 40, 41 

Naples, 122 

Navier, Claude-Louis, 69 

navigational aids, 150— i 

Nelli, Giovanni Battista, 99, 100— i, 106 

section drawing of Cathedral, j 
Nemi, Lake, 119 
Nenno di Chello, 97 
Neri di Fioravanti, 7—8, 121, 157 

model for cupola (1367), 3, 6, 7, 8—9, 
10, 38, 45, 55, 87, 121, 131, 143 
Nero, Emperor, 27 

Domus Aurea (Golden House), 28 
Nero, Stefano del, 41 
Nervi, Pier Luigi, 164 
Nonius Datus, 83 

Opera del Duomo, i 
Orcagna, Andrea, 13, 168 (^2) 
orders, Greek architectural, 26—7 
Orsanmichele, Florence: St John the 

Baptist, 44—5 
Ospedale degli Innocenti, Florence, 46 


Brunelleschi's Dome 

Padua, 52 

Palazzo Vecchio, Florence, 3, 4 
Pandolfini, Agnolo, 58, 59, 164 
Pantheon, Rome, 9, 10, 27, 28, 29, 30—1, 

Pappus of Alexandria: Mathematical 

Collection, 65 
patent, first, 114 
perspective, 35—6 

Brunelleschi's experiment, 35, 36—7, jy 
Perugia, 16 

Petronius: Satyricon, 32 
Piazza dell'Opera, Florence, 16 
pigeons, nesting, 97 
Pisa, 16, 60, 113, 114, 118 

'Leaning Tower', 8, 149 
Pisano, Andrea, 47, 132 

Baptistery doors, 14—15 
Pistoia, 15, 25, 74, 124, 167 
plague, the, 4, 14, 17, 18, 23, 89 
Pliny the Elder, 35, 43, 103 
Plotinus, 35 
plumbers, 74 
Plutarch, 65, 103 
Pointed fifth, see cjuinto acuto 
Ponte Vecchio, Florence, 8 
'pozzolana concrete', 27, 30 
Prato Cathedral, 34 
prisons, 134 

Proclus of Alexandria, 65 
Propertius, 32 
prostitutes, 22, 129 
Ptolemy I, King of Egypt, 126 
pyramids, Egyptian, 103—4 


marble, in— 12, 148 

sandstone, 2, 72—3, 120, 130 
Quintilian: Institutio oratorio, 32 
(juinto acuto, 10, 87—8, 88 

Raphael, 34 

relics, 23—4, 32, 140—1 

Ridolfi Chapel, San Jacopo sopr'Arno, 

Florence, 46—7, 86, 121 
Robbia, Luca della, 13 
Rome, 20, 23—7, 31—2, 46, 104 

Arch of Constantine, in 

Baths of Diocletian, 24, 27 

Baths of Trajan, 31 

Black Death, 23 

Colosseum, 27 

Forum, 23 

Golden House of Nero, i& 

Mausoleum of Augustus, 23 

Palazzo dello Sport, 164 

Pantheon, 9, 10, 27, 28, 29, 30—1, 55 

St Peter's, 90, 148, 163, 165, 169 (M5) 

San Paolo fuori le Mura, 24 

Santa Croce in Gerusalemme, 23 

Santa Maria Maggiore, 24 

Temple of Fortuna Virilis, 27 

Temple of Jupiter, 23 

Temple of Vesta, 174 (aii) 

Theatre of Pompey, 23 
rope-making, 60 
rota magna (treadmill), 59, 60, 120 

Sacchetti, Franco, 136—7 

safety measures, 96—7, 160 

St Denis, abbey of, 157 

St John the Baptist (Orsanmichele), 

St Paul's Cathedral, London, 163, 169 

St Peter's Cathedral, Rome, 90, 148, 163, 

165, 169 («5) 
salaries, 48, 52, 53, 91, 119, 130, 136 
Saldae, Algeria: aqueduct, 83 
Salisbury Cathedral, England, 30 
San Jacopo sopr'Arno, Florence: Ridolfi 




Chapel, 46—7, 86, 121 
San Lorenzo, Florence, 46, 121, 1^3, 135, 

San Marco, Florence, 155 
San Petronio, Bologna, 7 
San Vitale, Ravenna, 168 («5) 
sandstone chains (for cupola), 55, 56, 59, 
63, 64 
first, 72, 7j, 73-5 
second, 75, 92 
third, 120, 121 
fourth, 141, 143—4 
sandstone quarries, 2, 72—3, 120, 130, 162 
Sangallo, Antonio da, the Younger, 90, 


Santa Felicita, Florence: Barbadori 

Chapel, 46—7, 121 
Santa Maria degli Angeli, Florence, 130 
Santa Maria del Fiore Cathedral, 3, j, 6, 

acquires name, 33 

consecration, 139—41 

consecration of cupola, 141— 2 

foundation stone laid, 4 

nave, 6, 87 

sphere, 71, 145 

tambour, 9, 33 

see also models, architectural 
Santa Maria Novella, Florence, 46 
Santa Reparata, Florence, 3, 4, 33 
Santa Sophia, Constantinople, 6, 76 
Santa Trinita, Florence, 121 
Santo Spirito, Florence, 53, loi, 121 
Scala, Bartolomeo: Historia Jlorenttnorum, 

secret codes, 19, 25—6, 104, 146 
Seneca: Moral Letters, 158 
Settignano, 72 
Severus (architect), 28 
Sforza, Count Francesco, 129 

Siena, 16, 25, 126 

Signa, 113 

Silk Merchants Guild, 46, 133, 135 

Silvestri, Raynaldo, 133, 134 

slaves, 4, 100 

Sophocles, 65 

Sostratus of Cnidus, 126 

staircases (in dome), 160—2 

Stella (crane), 67—8 

Stinche, the (prison), 134 


apprenticeships, 73 

conscription, 16 

deaths, 54, 97 

master masons, 47—8 

measuring devices, 84, 85—7 

safety measures, 96—7, 160 

salaries, 130 

unemployment and strikes, 97, 98, 130 

use of tracing-floors, 84—5 

working conditions, 51, 52—4, 160—1 

see also brickwork (of cupola); 
sandstone chains 
Strabo, 65 
strikes, 97—8 

Strozzi, Giovanni Battista, 104—5, 107 
Sulla, Lucius Cornelius, 22 
Sultaniya: tomb of Oljeitii, 76 
Sybaris 126 

Taccola, Mariano, 66, 114, 119, 126—7, 1^8 

De ingeneis, 115, 126 

De machinis, 11^ 

drawing of // Badalone, 115, ll6 

drawing of ox-hoist, 6l 
Tacitus: Annals, 32 
Tibullus, 32 
timber supplies 39 

for castello, 68, 71 

for ox-hoist, 60 


Brunelleschi's Dome 

for scaffolds and platforms, 51 

for wooden chain, 75—6 
Torrigiani, Pietro, ^4 
Toscanelli, Piero, 149—50, 151— 3 
tracing-floors, 84—5 
tramontana, 68 
Trassinaia quarr^', nr Fiesole, 73, 120, 130, 

treadmills, 59 
Troves Cathedral, France, 8, 42 

Uccello, Paolo, 13 
Ufficiali deirOnesta, 129 
UfFiciali di Norte, 129 
Uffitiales cupule, 47, 48, 49 
Umiliati monks, 2 
unemplovment, 97, 130 

Valdilamone, battle of, 123 

Valeggio: dyke, 126 

\'asari, Giorgio, 34, 47 
Last Judgement, 161, 165, 166 
Lives of the Artists, 41, 42, 43, 68, 98, 

137. 155. 159 
verde di Prato (marble), no 
Verrocchio, Andrea del, 13, 71 
\^ia Appia, 24, 32 
Via dei Calzaiuoli, Florence, 4 
Visconti, Bemabo, 16 
Visconti, Filippo Maria, Duke of Milan, 

122-3, 128-9, 137 
Visconti, Giangaleazzo, Duke of Milan, 

16—17, '8, 20, 123, 126 
Vitruvius: De architectura, 35, 56^, 59 

Viviani, X^incenzo, 43 
Voltaire, 21 

War of the Eight Saints, 23 
weaponry', medieval, 125 

and melting of bronzes, 19 
Wenceslas IV, Emperor, 16 
Westminster Abbey, London, 23, 97 
Westminster Hall, London, 85 
wine drinking, 51, 54, 97 
wood, see timber supplies 
wooden centring, see arch construction 
wooden chain (for cupola), 75—7, 78—80, 

89, 162 
wool industry, 2, 17 
Wool Merchants Guild. 6, 41, 46, 47, 

48, 161 
workmen/craftsmen, 2 

feast davs and holidays, 52, 139—40 

food and drink, 53—4, 97 

hours worked, 52—3 

injun' and death, 54, 97 

labour shortages, 4 

plumbers, 74 

safety measures, 96—7, 160 

stonemasons, see stonemasons 

unemplovTnent, 97, 130 

unskilled labourers, 51—2 
Wren, Sir Christopher: St Paul's 
Cathedral, 163, 169 (05) 

Zagonara, battle of, 123 
Zenobius, St, 141, 156 
ziggurats, Sumerian, 102 


'During the rwenn-five years he spent building the monument that defines the cit> of 
Florence, Filippo Brunelleschi lost his bed in a freak flood and accidentally sank 100 
tons of fine white marble in a riverboat of his own design. Ross King deftly lays a score 
of these high Renaissance adventures into the brickwork of the rising dome. As each 
novel feat of genius engineering flowers high aboveground, details of scandals and 
pranks blow up from the cit> streets to create an altogether enchanting tale.' 
Dava Sobel, author of Longitude 

Even in an age of soaring skyscrapers and cavernous sports stadiums, the cathedral of 
Santa Maria del Fiore in Florence, with its immense, terracotta-tiled cupola, still retains 
a rare power to astonish. Yet the elegance of the building belies the tremendous labour, 
technical ingenuit}' and bitter personal strife involved in its creation. For over a century 
after work on the cathedral began in 1296, the proposed dome was regarded as all but 
impossible to build because of its enormous size. The greatest architectural puzzle of its 
age, when finally completed in 1436 the dome was hailed as one of the great wonders 
of the world. To this day, it remains the highest and widest masonry dome ever built. 

This book tells the extraordinar\' story of how the cupola was raised, from its 
conception to its consecration. Also told is the ston.' of the dome's architect, the brilliant 
and volatile Filippo Brunelleschi. Denounced as a madman at the start of his labours, 
he was celebrated at their end as a great genius. His life was one of ambition, ingenuity, 
rivalr>- and intrigue - a human drama set against the plagues, wars, political feuds and 
intellectual ferments of Renaissance Florence, the glorious era for which the dome 
remams the most compelling symbol. 

'Compelling... professional jealousy, comminee intrigue, feats of bluff and fascinating 
scraps of obsolete lore... Where Lofigitude had ocean wastes, Brunelleschi's Dome has 
vertigo.' William Weaver, Spectator 

'An adventure yarn set on the wild frontiers of human knowledge... abounding with 
excellent stories.' Jan Dalley, Fuiaucial Tunes 

'A wonderfully vivid little book.' Michael Prodger, Daily Telegraph 


Cover: architectural plans from Giovanni Battista N'elli. Ptante e alzJtt tntenori ed esterni 
dell'insigne Chiesa dt S. Maria del Fiore (1755) 

ISEN 0-7126-6480-7 

9 780712 "6G4806 


Random House 

20 Vauxhall Bridge Road 

London SWIV 2SA 

Histor\/Art Histor>' 

(^ uooo