The vast nave with nine bays of this old abbey church, which dates from the 11C, was inspired by the Benedictine abbeys. It leads to the tomb of Queen Matilda, founder of the Abbaye-aux-Dames (Abbey for Women). Adjoining the south transept is an attractive 13C chapel; also look out for the historiated capitals and the early 18C fresco on the oven vaulting. Go down into the crypt to admire its close-set columns and the Last Judgement on one of the capitals.