During World War II, Allied bombing forced Germany to move its industry underground.<\/p>\n
These facilities were dedicated mainly for the military industry. One of those facilities, whose official name was Project Schwalbe I and codenamed Eisenkies<\/strong>, was installed near the city of Hemer, 28 kilometers southeast of Dortmund, in western Germany, taking advantage of the Menden mine. According to the website Battlefieldsww2.com<\/a>, < strong>The construction of this factory began in the fall of 1944 to produce synthetic fuel<\/strong>, especially for the Messerschmitt Me-262 Schwalbe, a model famous for being the world's first mass-produced jet fighter.<\/p>\n To build this factory, the Nazi regime used 10,000 slave workers<\/strong>, mostly prisoners of war. In total, they removed 800 tons of limestone over 10 months. The construction of the factory was stopped in March 1945, without being completed<\/strong>, due to the advance of the allies. Finally, the US Army freed the hundreds of slave workers who had been left there by the Nazis. It is one of the few underground factories from World War II that were not destroyed<\/strong> and, according to the aforementioned website, it is used today as a training place for the special forces of the German Police.<\/p>\n
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