The cathedral's freestanding bell tower, 56 metres of Pisan-Romanesque marble in eight ringed storeys, leans 3.97 degrees off vertical. The lean is the famous bit, but the architecture is the better story — every arcade is a small masterpiece, and the whole thing is far more beautiful than the postcards suggest. Climb if you can; the 294 steps spiral up an inner staircase, and the dizzying sense of slope under your feet at the top is unforgettable.
Tickets are timed and booked online in advance. In high season they sell out a week ahead. Children under eight are not allowed up. You will have to leave bags at the cloakroom before climbing, and the climb itself takes about half an hour including the slot at the top.