Immaculée-Conception Basilica, Boulogne sur Mer
Boulogne-sur-Mer, FR
The present basilica, under the name of Notre-Dame, was built in the 19th century on the ruins of a medieval building. The building rests on one of the largest crypts in France (100 metres long and with a surface area of 1,400m²), which was laid out during the construction work on the foundations of the Romanesque crypt.