This understated cathedral was begun in 1075 and largely rebuilt in the 13th century. The freestanding church tower went up in the 15th century; the spire dates from the 19th century, when its predecessor famously toppled over. Inside, three storeys of beautiful arches sweep upwards and Romanesque carvings are dotted around. Interesting features to track down include a smudgy stained-glass window added by artist Marc Chagall in 1978 and a glassed-over section of Roman mosaic flooring.
On the left as you enter there's a small exhibition on the history of the building and little further on the treasury displays heaps of church plates and an interesting collection of 13th-century oak chests. The peaceful cloisters are home to an excellent cafe, all the profits from which go to the upkeep of the cathedral.