Against great odds, the Allied airmen imprisoned at the Nazi POW camp Stalag Luft III secretly engineered three escape tunnels they named "Tom," "Dick," and "Harry." They used only tools that they could manufacture themselves out of tin cans, and they scavenged building materials from the camp. When finished, they carried out one of the greatest mass escapes ever. This incredible feat was the basis for the movie, The Great Escape.
In case you haven't seen that rerun on TV for awhile, here's an interactive map, drawn after the war by one of the POWs, Ley Kenyon, which explores the remarkable story of Harry, the 300-foot tunnel that 76 men snuck through during their getaway on the night of March 24-25, 1944.