The Caves of Cerdon In beautiful surroundings, under the historical ruins of a fortified town, the cliff houses a renowned underground world. A large lake once flowed through the cliff. The resulting subterranean passage, unique to Europe, allows the visitor to discover the path of the ancient river from its underground origins to its resurgence in the valley. Galleries lead to a large hall,«La Fromagère», embellished by one of the most beautiful porch in France. Grottes du Cerdon – 01450 La Balme – Phone: (33) 4-74-37-36-79