Catacombs

Will Hunt explores Paris beneath the surface during a 14-mile trek underground with a group of urban explorers, and finds subterranean sights to rival those found on the famous streets above.
Nov 11, 2012   Intelligent Life
Beneath Paris is an underground network of tunnels and quarries, long closed to the public. <em>National Geographic</em> takes a tour of this forbidden part of the city, where urban explorers keep tradition alive.
Feb 3, 2011   National Geographic
A new mapping project is creating a comprehensive 3D image of the catacombs beneath Rome.
May 7, 2009   BBC