Discover the Notre-Dame and Saint-Thyrse cathedral or more commonly called Notre-Dame des Pommiers, harmoniously combining Romanesque art and Lombard architecture. This building divided into three naves ending each on an apse, was built in the 12th century and enlarged by the construction of several side chapels between the late 13th/ early 14th century and the 17th century. This monument was classified as a Historic Monument in 1840. The cathedral is the only witness of the primitive episcopal group. The building houses many paintings, the oldest of which date back to the 16th century. The major work is a magnificent altarpiece carved by Lalozière in the 17th century and serving as a showcase for two paintings by the painter Nicolas Mignard. A rich set of walnut stalls with mercies dating from the 17th century completes this set. Several sculptures are also to be discovered. The organ was installed in the 19th century.