parisbynumbers.com

Descend under the Paris streets, and alongside the sewers, the metro tracks and all the basements you’ll find something entirely more unusual - some 300km of ancient tunnels.

Paris’ unusual (and legendary) subterranean network was created as far back as the 12th Century, as Paris’ medieval citizens quarried out gypsum and limestone to help build their new and expanding city. They left behind a true labyrinth of passageways and vaults, some less stable than others - in the eighteenth century the city was plagued with road collapses as the weakest gave way.

The Catacombs of Paris, under Place Denfert Rochereau in the 14th arrondissement, represent a small and publicly viewable sample of this massive subterranean network. In 1785, with Paris cemeteries full to bursting with centuries of dead, the city authorities decided to begin interring it’s citizens within the empty tunnels - and continued it’s plan for more than a hundred years. By 1885, when the practice ground to a halt, the bones of more than six million Parisians had been delivered underground - and now line the walls, ceilings and floors of the catacombs, which has been a morbid tourist attraction for more than a century, and which can still be visited for a handful of euros today.

The catacombs represent only a tiny portion of the full network, which extends more than 170 miles around the city. The underground tunnels hold a important part in Paris’ turbulent history - they were used as safe harbour by rebels and government forces alike during the various civil conflicts that have shaken up the city, from the original Revolution of 1789 right through to the Paris Commune (1871) and beyond. Indeed, during the occupation of Paris by Hitler’s forces during the second world war, both German troops and bands of French Resistance Fighters made homes under the ground, and remnants of their residence can still be discovered by the most adventurous of explorers.

In the later half of the twentieth century, the tunnels have becoming something of a magnet for Parisian sub-culture. It is illegal, and extremely dangerous, to descend unauthorised into the tunnel system, and a small contingent of Paris police patrol when required. But numerous groups and individuals still explore, and attempt to map, the curious underground world: many looking for the numerous ossuaries that have not been opened to the public; others planning eccentric parties; some undertaking much more unusal pursuits. In 2004, a make-shift bar and cinema was discovered in a cavern under the 16th arrondissement. Protected from prying eyes by simple CCTV and a rudimentary security system, it had a power supply and three phone lines, and was only discovered by chance during a police exercise.