La Coupole, also known as the Coupole d'Helfaut-Wizernes and originally codenamed Bauvorhaben 21 or Schotterwerk Nordwest, is a Second World War bunker complex in the Pas-de-Calais department of northern France, about 5 kilometres from Saint-Omer, and some 14.4 kilometers south-southeast from the less developed Blockhaus d'Eperlecques V-2 launch installation in the same area. Wikipedia