Although Our-Lady is a Gothic church, it was found on the foundation of the former Romanesque chapel, destroyed in 1157. People were so happy, when they decided to re-raise the church, said a man called Guy de Bazoches, canon in the 12th century. Knights, rich and poor gathered around wagons which brought stones, in order to unload them!
The church was consecrated in 1332 by bishop Pierre de Latilly. In the 13th century, they replaced the Romanesque windows by larger stained-glass windows. Romanesque nave and transept date back to the 12th century, covered by a vault after 1157. The choir dates back to the 13th century. The 4 towers were crowned by spires in the 14th century, but three of them were destroyed during the Revolution.
Did you know they kept here for a long time... the Jesus navel's relic?! They created for it a reliquary in the beginning of the 15th century, that we can see nowadays in Cluny medieval museum (Paris). Pilgrims, as you probably guessed, came here in a body. But in the 18th century, a lord called Mr. De Noailles, count of Châlons, proved that the relic was a false one, and destroyed it right away!