An abandoned eerie structure in France could have doomed the Allies in World War II, and new discoveries at this mysterious site reveal the truth behind top-secret Nazi plans to unleash apocalyptic destruction. Germany built the Blockhaus d'Éperlecques between 1943 and 1944 outside the French town of Watten. It was one of the largest Nazi bunkers ever constructed to serve as a launch site for V2 missiles targeting London and southern England. Plans for the facility included storage for 108 missiles and two launch pads. Severe damage from heavy Allied bombing prevented its completion.