How Brunelleschi Engineered Florence’s Iconic Dome
No one who travels to Florence can help seeing the dome of the Cathedral of Saint Mary of the Flower. That’s true not just because of its sheer looming physical presence over the rest of the city, but also because of its importance as an achievement in various kinds of history, from that of engineering to architecture to religion. Its story is told by art historians Beth Harris and Steven Zucker in their new Smarthistory video above, which begins in the year 1417. At the time, Zucker explains, Florence had a “huge” problem: the groundwork for its ambitiously large cathedral had been laid a century before, but nobody knew how to build the dome for which its plans called.
The assumption, says Harris, was that “by the time they had to build it, they would figure out how to do it,” a reflection of both the more relaxed speed of construction in the fifteenth century, as well as a pace of innovation that must have felt rapidly on the increase.
Such a structure hadn’t been built since the Pantheon in antiquity, the outdoing of which would, at least in theory, confirm Florence’s reception of the torch of civilization from Rome. But none of the traditional techniques could support a dome of this size, atop so high a tower, during construction. Salvation eventually came in the unpromising form of Filippo Brunelleschi, an architect, sculptor, and goldsmith without much of a résumé — but, crucially, with a deep understanding of the Pantheon.
“Brunelleschi realized that hemispherical domes function in a self-supporting manner if they’re constructed out of self-supporting concentric circles,” Zucker says, and his challenge was to use that knowledge to build an octagonal dome. This involved designing two domes, a thick inner one covered by a thin outer one. Drop €30 on a ticket, and you can ascend the stairs through the inter-dome gap yourself. There the walls reveal the herringbone brick pattern that kept the structure stable; at a larger scale, those bricks form structural elements, much like oversized versions of the stones used to build arches since time immemorial. Regarding almost any picture of Florence, your eye may go straight to the cathedral, drawn both to the dome and to the splendor of its other era-mixing architectural features. But only from the inside can you understand how it all works.
Related content:
How the World’s Biggest Dome Was Built: The Story of Filippo Brunelleschi and the Duomo in Florence
The Beauty & Ingenuity of the Pantheon, Ancient Rome’s Best-Preserved Monument: An Introduction
Historian Answers Burning Questions About The Renaissance
Based in Seoul, Colin Marshall writes and broadcasts on cities, language, and culture. He’s the author of the newsletter Books on Cities as well as the books 한국 요약 금지 (No Summarizing Korea) and Korean Newtro. Follow him on the social network formerly known as Twitter at @colinmarshall.