Donald Pittenger looks back at La Ligne Maginot — as it was seen before the war:
When the drawing was made, details of the Maginot Line were military secrets. Even though the Germans had aerial photos of some of the fortresses under construction and might have had spies in the work crews, the public was told about the Line only in broad-brush form. For example, it was revealed that it was a system of underground fortresses placed near enough to one another that their artillery fire would be mutually-supporting. The fortresses were self-contained, troops living in underground barracks with support facilities such as command-posts, kitchens, mess-halls, dental clinics, operating rooms and recreation facilities.Each fort had its own electrical power generation system for use in case the national power grid (and its buried lines to the fortress) was disrupted. Also underground were artillery magazines and other storage facilities. Gun emplacements were on the surface, but heavily protected by reinforced concrete and steel. Tying it all together were underground electric railroads.