The cathedral on Piazza della Repubblica is the architectural set piece of the old town. The white travertine facade is a clean piece of late Tuscan Gothic from the 14th century — a single rose window over a pointed portal carved with foliage and small figures — while the interior is mostly a calmer 16th-century reworking with a few earlier elements, including a pre-Romanesque marble altar front.
It is rarely busy and a good place to step out of the midday sun. The piazza outside is the natural meeting point of the town and the start of the evening passeggiata.