When most people think of Paris, they picture the Eiffel Tower, croissants, or maybe dinner by the Seine. What you probably don’t imagine is a large, underground graveyard with ghost stories, underground cults and 300 kilometers of forgotten tunnels. It’s called the Paris Catacombs, and it’s full of bones, ghosts and strange mysteries.

The story of the Paris Catacombs begins in the late 18th century. Paris had a very big problem: death. So many people had died, especially during plagues, that cemeteries like Les Innocents were so overcrowded that corpses were spilling into surrounding streets. Bodies were dumped into mass graves, but some were so packed that bodies were rotting and causing outbreaks of disease, which did not help their problem. People became maniced and the city decided they needed a better place to put the dead. 

Under Paris lies a vast network of limestone quarries, some dating back to Roman times. The limestone was used to build much of the city, including famous buildings like Notre-Dame. By the 1700s, these quarries were causing structural problems on the surface because streets and buildings were collapsing due to the hollow ground beneath them. The city decided to solve two problems at once. By moving dead bodies into the abandoned limestone quarries, Paris would have a place to put their dead and use their bodies to support the city.  Starting in 1785, workers began digging up bones from cemeteries and moving them into the tunnels. The transfers continued for decades, and by the end, over six million Parisians had been moved underground. Louis-Étienne Héricart de Thury, a mine inspector, later arranged many of these bones into beautiful patterns. Skulls were stacked like bricks and femurs laid in symmetrical designs. It was meant to be respectful and be art. However, it also became something else. Paris was becoming a major tourist city, and the catacombs offered something totally different than the Eiffel Tower or art museums. The Paris Catacombs became a tourist attraction mainly because of their unique history, creepy atmosphere and the number of bones underground. Writers, artists and travelers started telling scary stories about the catacombs. That made even more people want to see them for themselves.

It’s one thing to walk among the dead. It’s another to feel them walking with you. Visitors to the public ossuary, a 1.5 km stretch of the 300 km labyrinth, often report unexplained experiences. Visitors to the Paris catacombs regularly report seeing ghosts, hearing disembodied voices coming from the walls, witnessing strange orbs and lights and being touched, only to find no one when they turn around. Yes, some could say this is just paranoia and it’s purely people’s imagination getting the best of them, but one particularly haunting story speaks of a man named Philippe, an amateur explorer who ventured into the off limits sections and was later found dead, disoriented and starved. The footage from his camera, recovered years later, is said to show him descending deeper into the dark, growing increasingly panicked before the footage abruptly ends. His final recorded words were, “They’re watching me.”

But the dead aren’t the only ones wandering the tunnels. Only a small part of the catacombs is open to the public, the rest is hidden and off-limits. But that doesn’t stop some people from sneaking in. They’re called cataphiles, urban explorers who know how to get inside using secret entrances in sewers, metro stations or even basements. They use maps and flashlights and have turned the tunnels into a secret society of sorts. They find hidden chambers, paint murals, host secret concerts and even hold dinner parties in the catacombs. One of the most famous discoveries came in 2004, when police stumbled upon an underground cinema with projection equipment, a stocked bar, a functioning power grid beneath the Palais de Chaillot and a note that read, “Do not try to find us.” However, even cataphiles tell stories of strange chanting in the dark, pentagrams drawn in bone dust and chambers where the air turns ice cold for no reason.

The Paris Catacombs are one of the most mysterious and spooky places in the world. They were made to solve a real problem, but over time they’ve become something much darker. If you ever visit, stay on the marked path. Otherwise, you might not make it back out.