The Government Bunker (Regierungsbunker) in Germany was a massive underground complex built during the Cold War era to house the German government, parliament and enough federal personnel needed to keep the government working in the event of war or severe crisis. Located only about 25 kilometres (16 mi) south of Bonn, it was one of the best kept secrets of West Germany.
The bunker complex below the vineyards and forests along the river Ahr was built inside two disused railway tunnels of a former strategic railway line built in preparation of World War I but never entered into service. After the war, during years of recession, the German state railway company lost interest in the line which was of no economic value and finally abandoned it.
Between 1930 and 1939 the disused railway tunnels were used to farm mushrooms to gain independence from having to import French fungi. During the later phase of World War II several arms manufacturing companies occupied the tunnels and a huge concentration camp for forced labourers was erected outside the protective cover of the tunnels, which was also referred to under the code name Lager Rebstock (Camp Vine). Inside the tunnels was a construction facility for manufacturing ground equipment and mobile launch pads for the V-2 rocket. With increasing Allied air raids at the end of the war, the tunnels served as makeshift air-raid shelters.
A small part of the once-secret site is now open to the public as Government Bunker Documentation Site, while the vast majority is abandoned and sealed.