To access the roof of the French comedy, you must go through the Constitutional Council, guarded by the gendarmerie. The place is significant, but so beautiful that one wonders why it does not officially open to visitors ...

The reservoir of Saint-Denis has two goals. Fight against flooding by optimizing draining and treat the pollution by settling the water.

Setting up a photo exhibition in the underground quarry of Saint-Leu d'Esserent by Arnaud.

Photo by G. Arnaud. The photographs can be viewed on the personal website.

The Bridge on the Mulatière is a work of almost 200 meters long. He was carried away by a flood in 1840. Rebuilt by the company Levallois-Perret (formerly Eiffel) in 1916, he was destroyed by the Germans in 1940 and 1944. Contemporary life is much quieter. It provides rail traffic in the Lyon Saint-Etienne.

Sometimes, the quarry collapse inside the walls! It is caused by the gypsum and the water.

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 mythical network. This network is considered as the greatest Lyons network (excluding sewers). Most of the existing maps were untrue or incomplete, probably intentionally to maintain the legend of mystery. Realistically, the size of the network is small, it develops within 2km. By cons, it is full of small surprises and intertwined levels that make it a very funny underground.

"The large sink" or "room of hanged people" is the locker room of minors. Besides saving space to hang clothes by a chain (with a padlock attached to the benches), the upper part of the room was warmer, facilitating the drying of clothes.

According to various persistent rumors, the galeries network could be open to the public in the near future, and maybe offering the preservation it deserves.

Meanwhile, various underground openings are bringing the presence of taggers. The most paradoxical is that these openings are often carried out by lovers of heritage assets and they open to vandals every time.

Most of the inhabitants of Lyon know that subsoil of the Croix Rousse and Fourvière is traversed by numerous galleries. Before the various prohibitions (and even after) to walk the subsoil of Lyon in the late 1980s, students were fond of underground walks. Moreover, there were few entries directly into schoolyards (now closed).