It was built on the site of a previous cathedral,
Santa Reparata, prompted by the magnificence of the new cathedrals in
Pisa and
Siena. At the end of the 13th century, the nine-centuries-old church of Santa Reparata was crumbling with age, as attested in documents of that time. Furthermore, it was becoming too small in a period of rapid population expansion. Prosperous Florence wanted to surpass in grandeur its Tuscan rivals, Pisa and Siena, with a more magnificent church, grander in size and more richly adorned at the exterior. This cathedral was, as a result, the largest in Europe when it was completed, with room for 30,000 people. It is now only exceeded in size by
Saint Peter's Basilica in the Vatican City,
Saint Paul's Cathedral in London, the
Seville Cathedral, and the
Milan Cathedral.
The new church was designed by
Arnolfo di Cambio in 1296 to be the largest
Roman Catholic church in the world (although the design was altered several times and later reduced in size). Arnolfo di Cambio was also the famous architect of the church of
Santa Croce and the
Palazzo Vecchio. He designed three wide naves ending under the octogonal dome, with the middle nave covering the surface of Santa Reparata. The first stone was laid on
September 9,
1296 by cardinal Valeriana, the first papal
legate ever sent to Florence. The building of this vast project was to last 170 years, the collective efforts of several generations.
After Arnolfo died in 1302, work on the cathedral slowed or was suspended during thirty years. The building drive got a new impetus, when the relics of San Zanobius were discovered in 1330 in San Reparata. In 1331, the Arte della Lana (Guild of Wool Merchants) took over the exclusive patronage for the construction of the cathedral and in 1334 they appointed
Giotto as overseer for the work. Assisted by
Andrea Pisano, he continued along di Cambio's design. His major accomplishment was the building campanile, but he died in 1337. Andrea Pisano continued the building, until he was stopped by the
Black Plague in 1348.
It was not until 1349 that work resumed on the cathedral itself under a series of architects, starting with
Francesco Talenti, who finished the belltower and enlarged the overall project with the apse and the side chapels, but did not alter the outside. After 1359 he was succeeded by
Giovanni di Lapo Ghini (1360–1369) who divided the center nave in four square bays. Other architects were
Alberto Arnoldi,
Giovanni d'Ambrogio,
Neri di Fioravante and
Orcagna. By 1375 the old church Santa Reparata was pulled down. The
nave was finished by 1380, and by 1418 only the dome was left uncompleted.
Drawing of Brunelleschi's dome.
The walls are covered in alternate vertical and horizontal bands with many-colored marble from
Carrara (white),
Prato (green), Siena (red), Lavenza and a few other places. These marble bands had to repeat the decorations of the Baptistery and Giotto's belltower. There are two lateral door, the Doors of the Canonici (south side) and the Door of the Mandorla (north side) with works of art of
Nanni di Banco,
Donatello, and
Jacopo della Quercia. The six lateral windows, notable for their delicate tracery and ornaments, are separated by pilasters. Only the four windows, closest to the
transept, admit light; The other two are merely ornamental. The clerestory windows are round, a common feature in Italian Gothic. The floor of the church was laid in marble in the 16th century.
During its long history, this cathedral has been the seat of the Council of Florence (1439), heard the preachings of
Girolamo Savonarola and witnessed the murder of
Giuliano di Piero de' Medici on
26 April 1478 (with
Lorenzo Il Magnifico barely escaping death).