Our aim is to examine the city's connection to its underground in a way no one has before: we will attempt to walk from the southern edge to the northern, using only catacombs, telecom tunnels, sewers and other hidden infrastructure. It is a 14-mile trek, every step illegal. — The Economist's Intelligent Life magazine
Will Hunt spent a few days and nights underneath Paris, as part of an expedition led by Steve Duncan, a photographer and urban historian from New York. The group discovered a parallel universe populated by: "cataphiles" - young, bohemian Parisians who use the tunnels as party venues, ossuaries and "An 800-year crawl".