Overview
It is the largest church in Italy after St Peter’s, built of Candoglia marble that the cathedral works still quarry under a concession granted in 1387. The style is Gothic that kept being resumed by later centuries with their own ideas, so the facade is a negotiation between the fourteenth and the nineteenth. Inside, a brass line set into the floor is a meridian of 1786, with a hole in the vault that puts a spot of sun on the correct date all year.
Highlights
Take the stairs to the roof rather than the lift; it is 250 steps, cheaper, and you arrive among the flying buttresses rather than above them. The archaeological area under the nave holds the fourth-century baptistery where Ambrose baptised Augustine. Dress code is enforced at the door, and the security queue at the piazza is separate from the ticket queue.