Forming the eastern flank of Piazza Duomo, the cathedral was built in 1086 but has since undergone various makeovers. The facade is 16th century, but the central bronze door, one of only about two dozen in the country, dates from 1179; the interior is a late-20th-century interpretation of what the original must once have looked like.

Of particular interest is the striking pulpit, supported by six twisting columns set on marble lions and decorated with flamboyant mosaics of peacocks and other birds. Note also how the floor is tilted towards the square – a deliberate measure to enhance the perspective effect. Entry is via the cathedral museum, displaying a modest collection of religious artefacts.