Quarries

Towns are located where they are for countless reasons, water, confluence of rivers and roads, agriculture. Another is access to building material. Many towns were built on the quarries the stone came from. Sometimes after the first floor was built, the occupant built his second floor out of stone quarried from his basement.

Paris sits on top of a network of subterranean tunnels and caverns stretching more than 300 miles--1900 acres--and extending 120 feet deep. Mostly limestone and gypsum (the famous plaster of Paris), the Romans carved sculptures and buildings, the French built everything from Notre Dame cathedral and the Louvre Museum to houses, then placed sewers, water mains, and tunnels for Métro lines.

Churchs dug crypts. Shelters were built during World War II and, later, garages for underground parking. Parisians call the multi-level maze gruyère (Swiss cheese)

Louis XVI mapped them to reinforce them, then moved graveyards into them--6 million bodies.

180 miles of tunnels are maintained by the Inspection Generale des Carrieres (IGC) and only one mile -the catacombs- is open to the public. A group called "cataphiles" have arisen who explore and exploit the gruyere. And they do not stay within the prescribed areas. They live, hold parties, sleep, create art with huge murals or complex structures--a National Geographic article has pictures of a four-foot-high limestone castle complete with drawbridge, moat, towers, and a little LEGO soldier guarding the gate. These people dive in abandoned wells and water sources, map areas for subsequent exploration.

A map of the Paris underground: