Miles of tunnels make up the underground structure of the Maginot Line, an underground structure built by the French to protect them during World War II, and shown here in 2010. The Germans broke through the Line—then arguably the most advanced fortification—in 1940. (Herald Post/David Walker)
Miles of tunnels make up the underground structure of the Maginot Line, an underground structure built by the French to protect them during World War II, and shown here in 2010. The Germans broke through the Line—then arguably the most advanced fortification—in 1940. (Herald Post/David Walker)