Beneath Paris, explorers uncovered a secret underground city lined with six million graves

Paris is celebrated for its grand boulevards, elegant cafés and iconic landmarks.

Yet beneath the pavements, far below the tourists and traffic, lies a second city that most people never see.The Paris Catacombs form an immense underground network of former limestone quarries stretching for hundreds of kilometres beneath the French capital.

Hidden entrances, flooded passages, forgotten chambers and walls built from human bones have long fuelled stories of mystery and adventure.

While the public ossuary attracts millions of visitors each year, much of the labyrinth remains closed, accessible only through concealed entry points known to experienced explorers.Venturing into these restricted sections reveals a very different side of Paris.

Here, traces of ancient quarry workers, wartime bunkers, underground artists and modern-day cataphiles coexist in a maze where history seems to accumulate layer upon layer.