They only know each other by nickname and are equipped with wellies and head-torches. This anonymity and the peculiar atmosphere resulting from the darkness, the silence and the dangers underground have a magic allure. They call themselves cataphiles. A hard core of 50-80 regularly moves around in the ramified network of catacombs underneath the French metropolis. For almost 1600 years, the underground of the French capital has been providing the stones needed as construction material for the city. A complex web of almost 300 kilometres of tunnels has resulted over time. Only a very small part of it in which human remains from the cemeteries of Paris were moved has been tapped into as a tourist attraction. The cataphiles, however, move in the huge damp and dusty areas in which access is prohibited. Cataphiles exist in a codified micro-community. Some have a very strong urge to explore, others are enchanted by the liberating world of minerals surrounding them. All share the same passion for the catacombs. After several kilometers of narrow passages and countless junctions and forking paths, we reach the first rooms arranged by cataphiles. These caves were consolidated and arranged by the hard work of the group. Even vital information (for instance on the constantly changing access points) is passed on by word of mouth. The city of Paris has the gully covers welded to seal these solitary gateways to the world below – a parallel world in which the absence of daylight creates an entirely different notion of the passing of time. Some intentionally stay hidden underground for long periods to experience some sort of hermitage, enjoying the caves as a retreat far away from the noise and stress of the city. All of them, unimpressed by the damp darkness, are united in their fear of losing their sanctuary.