The Crypt

Under the Notre-Dame Basilica in the old town of Boulogne-sur-Mer there is one of the largest crypts in France. A real gem!

One treasure may hide another... The unique architecture of the Notre-Dame Basilica of Boulogne-sur-Mer, which was inspired by Saint Paul’s in London, Les Invalides, the Pantheon and Saint Peter’s in Rome, always amazes visitors. What is even more astonishing is that one of the largest crypts in France is hidden right beneath it. It is a real labyrinth of 1,400 m2 in which some stunning items can be found.

The crypt is closed on Mondays

A time machine

When construction work on the basilica began in 1827 on top of the remains of the old medieval church, a Roman crypt in a remarkable state of conservation was uncovered. The story could have ended there (it had already become famous) if they had not decided to continue with the work of their predecessors. As a result, a 19th century crypt was created around the original crypt. This astonishing maze, which alone brings together the entire history of the city, can still be visited today. Every room will take you back in time. Excavations carried out in 2012 uncovered some unexpected treasures, such as a section of ancient wall indicating the existence of a Roman camp in Boulogne-sur-mer during the 1st century B.C.

An underground labyrinth

The crypt served as the foundations for the basilica, so you can amuse yourselves by trying to guess if you are under the choir or the nave. You can also have fun counting the number of treasures on show, but you will have to be systematic and patient! Over 400 items are displayed all around, including silverware and the reliquary of Saint-Sang offered to Notre-Dame by Philip the Fair on the occasion of the marriage of his daughter, bas-reliefs, lapidary from all eras and paintings, including the amazing paintings which decorate the walls. The Boulogne crypt houses no less than 4,000 m2 of painted murals. With or without a guide, you can enjoy more than 2,000 years of history. It is a pleasant way to explore the city in a different way. 

Great accessibility for disabled visitors

Don't forget your jumper, you might be surprised by the inside temperature !