Underground refuges in France

40 Years of Explorations and Studies

Underground refuges in Bavaria and Austria

Underground cities in Cappadocia (Turkey)

Souterrains and caves in Benin

Underground refuges in Ireland

Cave dwellings

Art in quarries (France)

Fauna and flora

Mushroom beds (France)

Quarries (creutes) during the First World War

Mine Warfare

Tunnels of Vietnam

Cliff "Cuevas" (Spain)

Underground quarries (France)

Ritual and religious underground passages (France)

Myths, Legends and Literature

Catacombs