We visited the catacombs, a large underground cemetery created in the 1700s. During the 1700s and 1800s, during the Hausmannian expansion of the city, bones from cemeteries throughout Paris were relocated to these catacombs. Millions are stacked here in neat piles, creating walls of bones on the sides of the hallways. The tour starts in dim, empty corridors, but leads to the cemetery as you walk through a door inscribed with “Stop. Here is the empire of death.”