This corridor is a passageway leading from the other side of the hill, where the underground quarry really begins.

A corridor consolidated in the salt mine of Berchtesgaden.

The stairs cross of the peak battery. The corridor down the room leads to the research center, while the two others leads to the main ramparts.

A corridor consolidated in the salt mine of Berchtesgaden.

One of the most interesting plates of the official ossuary. This part of the catacombs is hidden to the public.
It is inscribed "Catacombs low" while the corridor descends into a lower part of the quarry. The bones are placed in bulk.

Under the Trocadero Gardens, the park of Saint-Cloud, a few long corridors developed a total of about 300m.

Extraction of the Stone follows the geological slope. At the bottom of the galleries, a flat corridor allows to evacuate materials by truck. On the right, a horizontal corridor connects two superimposed levels.

A corridor in the large underground quarry Port-Marly Jaguar.

The corridor amphitheatres, under the roof of the ark.

Map of the quarry Montalets, level 2. This level is very big, with high corridors, some ponds and nice rooms.