After the completion of the main structure of the cathedral in 1418, a design for the dome over the nave remained to be determined. According to Michael Raeburn "The construction of the dome of Florence Cathedral (was) one of the germinal events of Renaissance architecture...The problem had been posed in the middle of the fourteenth century when the definitive plan for the octagonal crossing had been laid down. The diameter of the dome at 39.5 metres (130 feet) precluded the traditional use of wooden structuring to support the construction of the vault, while the use of buttresses as in northern Gothic cathedrals was ruled out by the building's design." With these issues in mind, the head architect was selected by Florence’s Wool guild through a competition in which the prospective architects were purportedly tasked with balancing an egg upright on a slab of marble. Filippo Brunelleschi won the challenge, beating his rival Ghiberti, who had early beat him in the competition for the baptistry doors. In his design for the dome, Brunelleschi was able to innovatively solve the problem of spreading due to hoop stress through his us of the catenary arch and vertical ribbing, and also invented new machines for hoisting materials to the dome and was responsible for one of the first patents to protect his inventions. The dome was completed in 1436 and became a symbol of Florentine Innovation, described by Alberti as "A structure so immense, so steeply rising toward the sky, that it covers all Tuscans with its shadow".

“Florence Cathedral.” Wikipedia, Wikimedia Foundation, 28 Feb. 2018, en.wikipedia.org/wiki/Florence_Cathedral.

“Florence Cathedral.” Archinomy, www.archinomy.com/case-studies/946/florence-cathedral.

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