Carved plate indicating location - Rue St Jacques sous l'hotellerie de la Herse (rue Saint-Jacques, under a hotel)
The "Saint" part of the street name was omitted during the French revolution when the plate was carved, and a small "st" (for Saint) was added later before "Jacques".
Catacombs of Paris (off-limit area), about 20 meters (60 feet) underground, under Paris city center.
This is a part of the 200 Km network of ancient tunnels not opened to the public, but regularly visited by trespassing urban cavers called "cataphiles". See more information in the album description.
This photo was taken using the 180mm Raynox fisheye extension. The barrel distorsion was later corrected in Photoshop using the Panorama-tools plugin filters.