In the catacombs under Paris, art and adventure mix in an exclusive world of creativity and freedom hidden from the world above.

PARIS — On a recent evening, a 31-year-old street artist led a small group through a dark tunnel off a disused train track in the south of Paris. After crouching, crawling and sometimes wading through water, using headlamps to light their way, they finally arrived in a chamber with vaulted ceilings about 10 feet high.

An artist known as Nobad and his friends in a gallery of the Paris catacombs. Regulars try not to reveal the tunnel entrances to outsiders.
An artist known as Nobad and his friends in a gallery of the Paris catacombs. Regulars try not to reveal the tunnel entrances to outsiders. © Dmitry Kostyukov for The New York Times

Nobad stencils European paintings with a twist, like Gustave Courbet’s “Desperate Man” in glow-in-the-dark paint. But the walls are covered with art, including paintings in the style of Egyptian tomb murals, grimacing black and orange devil faces, a giant multicolored parrot, and an abundance of graffiti. In one room, the walls are encrusted with mirror shards, and a glittering disco ball hangs from the ceiling. ... The term “catacombs” designates only a small part of this vast underground network, the fraction where the remains of six million Parisians were transferred in the 1780s from several of the city’s overflowing and unsanitary cemeteries. That ossuary is one of the rare parts of the network legally open to the public and has become a popular tourist attraction.