Duomo of Florence Timeline

The architectural choice made in 1367 was one of the first events of the Italian Renaissance, marking a break with the Medieval Gothic style and a return to the classic Mediterranean dome.

Image source: Filippo Brunelleschi

On 19 August 1418, the Arte della Lana announced an architectural design competition for erecting Neri's dome. Ghiberti, winner of the 1401 Baptistery doors competition, became Brunelleschi's lifelong rival.

Erection of the dome had begun in 1420, executed without modern understanding of physical laws or mathematical tools for calculating stresses, which were centuries in the future.

Image source: Florence Cathedral

In 1423, Brunelleschi was back in charge and took over sole responsibility. Although he executed an aesthetic plan made half a century earlier, his name is commonly associated with the dome rather than Neri's.

Construction of the lantern was begun a few months before Brunelleschi's death in 1446, and it was finally completed by his friend Michelozzo in 1461.

Image source: Michelozzo

The conical roof was crowned with a gilt copper ball and cross containing holy relics by Verrocchio in 1469. With this, the building started in 1296 was finally completed.

Image source: Andrea del Verrocchio

In 1475 the astronomer Paolo dal Pozzo Toscanelli pierced a hole in the dome 91.05 metres above the pavement to create a meridian line. Due to settlement and temperature movements it fell into disuse until restored in 1755 by Leonardo Ximenes.

Image source: Paolo dal Pozzo Toscanelli

Donatello, then in his early twenties, was commissioned in 1408 to carve a statue of David to top one of the buttresses, though it was never placed there. One statue lifted into place in 1409 proved too small to be visible from the ground and was taken down.

Image source: David (Donatello)

Between 1409 and 1411 Donatello made a statue of a sitting Saint John the Evangelist, which until 1588 stood in a niche of the old cathedral façade.

Image source: Mark the Evangelist

Between 1415 and 1426, Donatello created five statues for the campanile: the Beardless and Bearded Prophet (both 1415), the Sacrifice of Isaac (1421), Habbakuk (1423–25), and Jeremiah (1423–26).

Image source: Donatello

Paolo Uccello created this almost monochrome fresco in terra verde, painted to resemble bronze; it was transferred to canvas in the 19th century.

Image source: John Hawkwood

Above the main door is the colossal clock face with fresco portraits of four Prophets or Evangelists painted by Paolo Uccello in 1443; this timetable was used until the 18th century.

Image source: Paolo Uccello

Andrea del Castagno created the Equestrian statue of Niccolò da Tolentino fresco in 1456, painted to resemble marble in the same style as Uccello's Hawkwood monument; it was transferred to canvas in the 19th century.

Image source: Andrea del Castagno

A figure of Hercules in terracotta was commissioned from the Florentine sculptor Agostino di Duccio in 1463 and was made perhaps under Donatello's direction.

Image source: Agostino di Duccio

A statue of David by Michelangelo was completed between 1501 and 1504, although it could not be placed on the buttress because of its six-ton weight.

This enormous work covering 3,600 square metres of painted surface was commenced in 1572 by Giorgio Vasari and completed in 1579. Vasari finished The 24 Elders of Apocalypse near the lantern before his death in 1574.

Image source: Giorgio Vasari

In 2010 a fiberglass replica of Michelangelo's David was placed for one day on a rooftop buttress for a chapel's dome, evoking the sculpture's originally intended location.

Image source: David (Michelangelo)

The copper ball crowning the lantern was struck by lightning on 17 July 1600 and fell down, requiring replacement.

The first written evidence about cracks appears in a report by Gherardo Silvani dated 18 September 1639 referring to 'peli' ('hairs'). It is possible that the first cracks were caused by a strong earthquake in 1453.

In 1694 Giambattista Nelli and Vincenzo Viviani surveyed the cracks, recording two major cracks with a maximum width of 29 mm. A commission headed by Viviani concluded in 1695 that cracking was due to the dead weight of the buildings.

Image source: Vincenzo Viviani

The first most complete survey of the cracks was published in 1757 by the Jesuit Leonardo Ximenes, two years after he restored the meridian line.

Image source: Leonardo Ximenes

In 1934, Pier Luigi Nervi, head of a special commission established by the Opera del Duomo, observed that the cracks opened and closed with the seasons.

Image source: Pier Luigi Nervi

In 1955 the Opera del Duomo installed 22 mechanical deformometers, read four times a year to record variations in the width of major cracks in the inner dome. This system remained in service until 2009.

The cathedral underwent difficult excavations between 1965 and 1974, revealing remains of the earlier church of Santa Reparata.

A government culture agency decided in 1978 to restore the frescoes. Work undertaken between 1979 and 1995 required modern metal scaffolding anchored in holes filled with concrete in 1982.

Using software developed to model dam structures, researchers led by Michele Fanelli and Gabriella Giuseppetti built a computer model of the dome in collaboration with Italian agencies and the University of Florence.

Analysis by Chiarugi, Fanelli and Giuseppetti found the principal source of cracks was dead-weight effect from the dome's geometry, its estimated 25,000-ton weight, and insufficient ring beam resistance. In 1987 it was demonstrated that filling the 48 scaffolding holes had no impact on the dome's movement.

A survey completed in 1984 counted a total of 493 cracks of various sizes, sorted into categories identified by the letters A through D.

In 1987 a comprehensive digital system automatically collecting data every six hours was installed by ISMES in cooperation with the Soprintendenza. Data shows major cracks widening approximately 3 mm per century.

To assist monitoring of the dome, an extensive photogrammetric and topographical survey of the entire dome was commissioned in 1992 by the Soprintendenza.

During restoration work ending in 1995, the entire pictorial cycle of The Last Judgment was photographed with specially designed equipment and all information collected in a catalogue. The meridian line was also unveiled again in 1997.