Zoriah/www.zoriah.com Human bones and skulls litter a tunnel floor.

Deep below Paris’ winding streets lies a vast network of subterranean tunnels and caverns stretching more than 300 miles/777 kilometers. Formerly mines and quarries, the catacombs became a dumping ground for human remains in 1786 when Paris’ cemeteries began to overflow from generations of the dead. The catacombs have had many uses over the centuries, including housing members of the French Resistance and a German bunker during World War II.

Now Paris’ Catacombs are explored by small groups of urban adventure seekers and partiers called Cataphiles. They illegally descend into the tunnels to explore, dig, take part in parties — some of which last for days — and place new art and graffiti on the walls. Entering through the city’s sewer systems, metro tunnels and other secret entrances begins a game of cat and mouse between the Cataphiles and the French police unit tasked with patrolling the tunnels, the Catafics.

For years I have wanted to explore the Catacombs of Paris but have not been able to get access, as it is even very difficult for most Parisians to get connected with a group willing to take them into the tunnels. On a trip last year I met up with a group of Cataphiles who offered to bring me into their world and allow me to photograph a two-day descent into the Catacombs.

A Cataphile scales the walls of an underground corridor in hopes of discovering secret passageways or entrances.

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