A mythical network. This network is considered as the greatest Lyons network (excluding sewers). Most of the existing maps were untrue or incomplete, probably intentionally to maintain the legend of mystery. Realistically, the size of the network is small, it develops within 2km. By cons, it is full of small surprises and intertwined levels that make it a very funny underground.

A forgotten subway station, near the Maillot entrance of Paris.

One of the underground cathedrals of city's Defense, so called because the vacuum is very large. Before the attacks of September 11, 2001, the underground were opened in the Heritage Days. Since then, all visits are canceled

The viaduct Garabit is made entirely of metal. It was built by Gustave Eiffel & Cie in 1884 under the direction of the architect Leon Boyer. It is 564m long. Since the construction of the dam Grandval, a lake was formed under the viaduct, 95m below. Trademark Construction of Eiffel, it is no less than 678,768 rivets were used for construction.