This quarry is as beautiful as dangerous. The oxygen level can be low as 13%. It's very low, be carefull.

The limestone quarry of Chanaz is a smaller operating on three levels. The ceiling height is between 5 and 10m. Sometimes, holes in the floor let you see underground levels.

The network size is almost 4km developed. It was exploited from 1860 to the end of the Second World War to make cement. Portions was reused as mushroom farm thereafter (row crops and cultures in bags).

In this photo taken at the highest level, we see the intermediate level, row crop bottom right and even two holes overlooking the lower level. This is the most impressive part of the network with large volumes!

A beautiful underground sandpit, on two levels.

This sandpit on two levels is very fragile.

A view down to the lower level of the limestone quarry Chanaz.

The limestone quarry of Chanaz has been converted into mushroom farm once the site abandoned. Here is a mushroom farm, cultures arranged in line. The staircase leads to the upper level of the quarry.

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 3 levels of balconies on the Molitor swimming pool.

Map of the quarry called Montalets. This is the level 1 of five.