La Coupole

La Coupole (English: The Dome), also known as the Coupole d'Helfaut-Wizernes and originally codenamed Bauvorhaben 21 (Building Project 21) or Schotterwerk Nordwest (Northwest Gravel Works), is a Second World War bunker complex in the Pas-de-Calais department of northern France, about 5 kilometres (3.1 mi) from Saint-Omer, and some 14.4 kilometers (8.9 miles) south-southeast from the less developed Blockhaus d'Eperlecques V-2 launch installation in the same area. It was built by the forces of Nazi Germany between 1943 and 1944 to serve as a launch base for V-2 rockets directed against London and southern England, and is the earliest known precursor to modern underground missile silos still in existence.

• http://en.wikipedia.org/wiki/La Coupole