Schwalbe I

The Schwalbe I project was one of the largest secret construction projects of the Third Reich's U-relocation. The building with the original code name "Eisenkies" is one of the largest tunnel systems in the Sauerland and is located at the eastern end of today's urban area of Hemer on the border with today's Menden urban area near Oberrödinghausen. As part of the Geilenberg programme to secure the war-relevant petroleum industry from total destruction by Allied air raids, work began at the end of August 1944 on the construction of this gigantic tunnel system in the hidden Hönnetal of the Sauerland in the Emil 1 quarry of the Rheinisch-Westfälische Kalkwerke.

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