Insurmountable

Underground ammunition depot at the Siegfried Line, 1939

Workers at a dragon's teeth on the Siegfried Line, 1939

Dragon's teeth against tanks at the Siegfried Line, 1939

Workers at the Siegfried Line, 1939

German troops at the Siegfried Line, 1939

Artillery gun at the Siegfried Line, 1939

Soldiers of the Wehrmacht at the Siegfried Line, 1939

Bunker complex at the Siegfried Line, 1939

Prisons