The cab glides through Saturday morning. The great avenues are quiet, the shops closed. From a bakery comes the scent of fresh bread. At a stoplight a blur of movement draws my attention. A man in blue coveralls is emerging from a hole in the sidewalk. His hair falls in dreadlocks, and there is a lamp on his head. Now a young woman emerges, holding a lantern. She has long, slender legs and wears very short shorts. Both wear rubber boots, both are smeared with beige mud, like a tribal decoration. The man shoves the iron cover back over the hole and takes the woman's hand, and together they run grinning down the street.
Paris has a deeper and stranger connection to its underground than almost any city, and that underground is one of the richest. The arteries and intestines of Paris, the hundreds of miles of tunnels that make up some of the oldest and densest subway and sewer networks in the world, are just the start of it. Under Paris there are spaces of all kinds: canals and reservoirs, crypts and bank vaults, wine cellars transformed into nightclubs and galleries. Most surprising of all are the carrières—the old limestone quarries that fan out in a deep and intricate web under many neighborhoods, mostly in the southern part of the metropolis.
Into the 19th century those caverns and tunnels were mined for building stone. After that farmers raised mushrooms in them, at one point producing hundreds of tons a year. During World War II, French Resistance fighters—the underground—hid in some quarries; the Germans built bunkers in others. Today the tunnels are roamed by a different clandestine group, a loose and leaderless community whose members sometimes spend days and nights below the city. They're called cataphiles, people who love the Paris underground.