Duomo

The Gothic Duomo, with its white-and-green-banded facade, contains a key early-medieval treasure, the Corona Ferrea (Iron Crown), fashioned according to legend with one of the nails from the Crucifixion. Charlemagne, King of the Franks and the first Holy Roman Emperor, saw it as a symbol of empire, and he was not alone. Various other Holy Roman emperors, including Frederick I (Barbarossa) and Napoleon, had themselves crowned with it. It's on show in the chapel (from Tuesday to Sunday) dedicated to the Lombard queen Theodolinda.