Florence Cathedral

What is Florence Cathedral?
Florence Cathedral, formally known as Santa Maria del Fiore and commonly called the Duomo, is the great Gothic church at the heart of Florence, celebrated above all for the enormous brick dome that crowns it. Construction spanned nearly a century and a half and passed through the hands of several successive master builders, but it is the dome, engineered by Filippo Brunelleschi in the early fifteenth century, that transformed the building into one of the defining achievements of the Renaissance. It remains the largest brick dome ever constructed anywhere in the world.

How did the cathedral's construction begin?
Construction began on 8 September 1296 under the architect Arnolfo di Cambio, who laid out an ambitious Gothic plan intended to surpass the cathedrals of Florence's rival Italian cities. After Arnolfo's death the project passed to a succession of later architects, including Giotto, who took charge in 1334 and designed the cathedral's freestanding bell tower, and Francesco Talenti, who expanded the design further following the disruption of the Black Death. Progress on the main body of the cathedral continued steadily, even as the building's most difficult challenge remained conspicuously unresolved.

What problem did Florence face with the dome?
The cathedral's design called for an octagonal crossing roughly forty-five metres across, a span far greater than any dome successfully built since antiquity, and for decades the project simply left this enormous gap open to the sky. Traditional dome construction relied on temporary wooden centering to support the structure while it was being built, but a gap of this size made such scaffolding practically and financially impossible to construct. The cathedral effectively stood without a roof over its main altar for years, a visible symbol of a problem no one yet knew how to solve.

How did Filippo Brunelleschi come to build it? Brunelleschi, originally trained as a goldsmith, had already lost one major Florentine competition in 1401, when the commission for the Baptistery's new bronze doors went to his rival Lorenzo Ghiberti, prompting him to travel to Rome and study ancient architecture instead. In 1418, the cathedral authorities announced a new competition specifically for the dome, drawing designs from numerous architects, and Brunelleschi's proposal, though controversial and initially difficult for the judges to fully accept, ultimately won him the commission. His years studying Roman structures, including the Pantheon, had given him insights into ancient building techniques that none of his rivals could match.

What made Brunelleschi's approach so unconventional?
Rather than relying on flying buttresses or temporary wooden centering, both standard solutions elsewhere in Gothic architecture, Brunelleschi proposed a self-supporting structure that could rise gradually without conventional scaffolding, a claim many of his contemporaries found difficult to believe. He designed the dome as two separate shells, an inner structural shell and a lighter outer shell, connected by a system of internal ribs that distributed weight in ways no one in Florence had previously attempted. This approach demanded both extraordinary confidence and genuinely original engineering, since failure risked collapsing the most important building in the city.

How did Brunelleschi actually solve the engineering problem?
Construction relied on a distinctive herringbone brickwork pattern that allowed each course of bricks to help support the next as the dome rose, gradually locking the growing structure together without external support. Brunelleschi also designed specialised hoisting machines, including an ox-powered lifting mechanism with a reversible gear system, to raise the enormous quantities of stone and brick required to the dome's increasing height. These combined innovations, mechanical, architectural, and material, allowed construction to proceed steadily upward between 1420 and 1436 without the structure ever requiring the traditional wooden support Florence's builders had assumed was indispensable.

What happened between Brunelleschi and Ghiberti during construction?
Despite Brunelleschi's clear authorship of the winning design, cathedral authorities initially placed his old rival Ghiberti in a shared supervisory role over the project, a decision Brunelleschi deeply resented. According to tradition, Brunelleschi responded by feigning illness during a critical juncture in construction, forcing the project to grind to a halt until officials recognised that Ghiberti lacked the technical knowledge to proceed without him. Within a few years, Brunelleschi had secured effectively sole authority over the dome's construction, finally free of the shared credit that had so irritated him from the project's outset.

When was the dome completed?
The dome was structurally completed in 1436, and the cathedral was formally consecrated by Pope Eugene IV on 25 March that year, marking the effective conclusion of a construction process that had begun a hundred and forty years earlier. Brunelleschi lived to see his creation finished, though the decorative lantern crowning the very top of the dome was not completed until years after his death in 1446. The achievement cemented his reputation as one of the defining architectural minds of the early Renaissance.

What decorates the interior of the dome?
The dome's vast interior surface was eventually covered with an enormous fresco of the Last Judgment, painted by Giorgio Vasari and Federico Zuccari between 1572 and 1579, covering roughly thirty-six hundred square metres and ranking among the largest fresco cycles anywhere in the world. This elaborate painted scheme replaced an earlier, unfinished mosaic decoration that Brunelleschi himself had originally envisioned for the space. The scale of the fresco alone gives some sense of just how immense the interior of Brunelleschi's dome truly is.

What about the cathedral's famous colourful facade?
The cathedral's striking exterior, patterned in green, white, and pink marble, is in fact a comparatively modern addition, completed only between 1876 and 1887, centuries after the dome itself was finished. The original medieval facade had been left incomplete and was eventually demolished in the sixteenth century, leaving the cathedral's front conspicuously bare for hundreds of years before the current neo-Gothic design was finally realised. The finished facade deliberately echoes the marble palette already established by the nearby bell tower and Baptistery, unifying the entire piazza's appearance.

Why does it deserve a card?
Florence Cathedral stood incomplete for well over a century, its most important architectural problem unsolved, until a hot-tempered former goldsmith convinced a sceptical city that a dome of unprecedented size could rise without a single piece of supporting scaffolding. Brunelleschi's solution combined careful study of ancient Rome with entirely original mechanical invention, producing a structure that remains the largest brick dome on earth nearly six centuries later. Few buildings so perfectly capture the Renaissance conviction that ancient knowledge and new ambition could combine to achieve what previous generations had thought genuinely impossible.

Florence Cathedral is part of Volume III

Get the Deck