History of Italian Renaissance domes

Italian renaissance domes were designed during the Renaissance period of the fifteenth and sixteenth centuries in Italy. Beginning in Florence, the style spread to Rome and Venice and made the combination of dome, drum, and barrel vaults standard structural forms. Notable architects during the Italian renaissance were Filippo Brunelleschi, builder of the dome of Florence Cathedral, Donato Bramante, Andrea Palladio, and Michelangelo, designer of the dome of St. Peter's Basilica.

After years of considering options, Filippo Brunelleschi and Lorenzo Ghiberti were made joint leaders of the project to build the dome for Florence Cathedral in 1420. Brunelleschi's plan to use suspended scaffolding for the workers won out over alternatives such as building a provisional stone support column in the center of the crossing or filling the space with earth. The octagonal brick domical vault was built between 1420 and 1436, with Ghiberti resigning in 1433. The lantern surmounting the dome, also designed by Brunelleschi, was not begun until 1446, after his death. It was completed in 1467. He had also planned for a two-story external gallery and cornice to be built at the top of the drum where a strip of unclad masonry can be seen today. Although a portion of it was constructed on the southeast side beginning in 1508, work stopped after the visual effect was criticized by Michelangelo.

The dome is 42 meters wide and made of two shells. A stairway winds between them. Eight white stone external ribs mark the edges of the eight sides, next to the red tile roofing, and extend from the base of the dome to the base of the cupola. Each of the eight sides of the dome also conceal a pair of intermediate stone ribs that are connected to the main ribs by means of a series of masonry rings. A temporary wooden tension ring still exists near the bottom of the dome. Three horizontal chains of sandstone blocks notched together and reinforced with lead-coated iron cramps also extend the entire circumference of the dome: one at the base (where radial struts from this chain protrude to the exterior), one a third of the way up the dome, and one two thirds of the way up the dome. Only four major cracks have been observed on the inner dome, compared to about fourteen each on the domes of the Pantheon and St. Peter's Basilica.

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