Télégraphe is a small fort near the mountain pass with the same name. It was built between 1886 and 1893 at the end of a mountain ridge that dominated the valley of the river Arc. The space was very limited, so the designers has to squeeze all the functions in a small area. The fort also has a very strange feature: two entrances. The upper entrance gave access to the gun positions, the lower shown here was the way to the barracks.