A beautiful medieval cellar cave excavated by some groups in the area. 1800 tons of debris have been removed to give a breath of life to those underground. These caves communicate with each other on a good part of the hill. They share an old quarry, very small, very pretty and beautifully preserved.

Source: words collected during Heritage Days 2008

This place is called Quarrymen's footbath but it's particularity is to be the first geological drilling in Paris, in the oldest medieval quarry of Port-Mahon, close to the official Paris catacombs.

The stairway to the underground quarry of medieval Pontoise.

This place is called Quarrymen's footbath but it's particularity is to be the first geological drilling in Paris, in the oldest medieval quarry of Port-Mahon, close to the official Paris catacombs.

This place is called Quarrymen's footbath but it's particularity is to be the first geological drilling in Paris, in the oldest medieval quarry of Port-Mahon, close to the official Paris catacombs.