Salle du Grand Dôme

A cathedral made of minerals and a kingdom of seepage, the Salle du Grand Dôme (Hall of the Great Dome) offers what is doubtless the most majestic viewpoint of this entire, incredible visit. Its ceiling reaches a height of 94 metres. Like the other galleries, this immense hall is the result of very intense erosion over the last 2 million years. It is one of the largest underground halls open to visitors in France.

Just a few tens of metres above the dome, the surface and nature in the open air are present… who would have said so?

Édouard-Alfred Martel described the Salle du Grand Dôme as an unfinished chasm, since erosion stopped before creating a connection to the surface. Nowadays, the climate is not suitable for limestone erosion, and the structure remains stable. However, over a very long timescale, climate changes like those that have occurred since the start of the Quaternary Period could cause erosion to start again, with a second chasm opening up over hundreds of thousands or even millions of years.