The crypt is located beneath the square in front of Notre-Dame. Former wall of Lutetia, the Roman town ancestor to Paris, 4th century AD. Former wall of Lutetia, the Roman town ancestor to Paris, 4th century AD. Roman pier of a harbor. The Seine river now flows 55m from this location. Image of the area in front of Notre-Dame before the 1772 fire. Bath house rooms, used until the 5th century. Bath house rooms, used until the 5th century. Bath house rooms, used until the 5th century. Inside Labels