Flying buttresses hold up the 12th- and 13th-century Église St-Pierre. Once part of a Benedictine monastery founded in the 7th century, it was outside the city walls and thus vulnerable to attack; the fortress-like, pre-Romanesque bell tower attached to it was used as a refuge by monks, and dates from around 1000. The fine, brightly coloured clerestory windows in Église St-Pierre’s nave, choir and apse date from the early 14th century.