Les Halles is a largely subterranean site at the heart of the Paris metropolis that serves both as a major transport network hub and a shopping center. Placing more than three million people less than half an hour from the center of Paris, what was once called the “belly” of the capital concentrates passenger flows and extends the labyrinthine logic of the Metro. For many, it is an oppressive space to pass through, but for others it is also a mythological place associated with urban culture and the hip hop movement. The subject of this paper is the unique underground life produced by Les Halles. It is based on fieldwork combining approaches from ethnography, semiotics, and visual anthropology.