Although the construction of the Santa Marie del Fiore had begun in 1296 (plague and war impeded progress) it still wasn't finished by 1418. Since the city wardens had no idea how their model could be built, they held a competition for a design solution. The book recounts the amazing story of how a Florentine goldsmith with no formal architectural training achieved the feat. The top of the dome is 20+ stories high, so the details - especially the invention/use of machines - of how it was done in the 15th century are fascinating. I really enjoyed watching the NOVA special on PBS, The Great Cathedral Mystery, after finishing the book.