Florence's cathedral, Santa Maria del Fiore, was begun in 1296 with a plan for a huge dome over an eight-sided crossing about 45 meters wide. By 1418 the walls were up to the base of the dome, but no one knew how to build it. A dome that wide would normally be built over centering: a wooden framework holding up the masonry until it was complete. There was not enough timber in Tuscany to build one that size, and the city did not want Gothic flying buttresses.
In 1418 the city held a competition. Filippo Brunelleschi, a goldsmith turned engineer, won with a plan to build the dome without full centering. Work ran from 1420 to 1436; the marble lantern on top was finished later, after his death in 1446.
Looking closely: The dome. From the hills above Florence, the dome rises over the roofs like a red mountain, larger than anything around it. Eight white marble ribs climb from the drum to the lantern, dividing the red tile into eight curved panels. It is pointed rather than round in profile, a shape that pushes out less at the base. The lantern on top, a small temple of white marble, locks the ribs together and lets light into the space below.
Key idea
Why it works
Worked example: Why not buttresses?
- Its pointed profile pushes outward less than a round dome would.
- Hoop-like chains around its base hold it in, the way hoops hold a barrel.
- Its double shell and ribs make it strong but lighter.
Answer: With its shape, internal chains and a double shell, not flying buttresses.
Common mistake