La Coupole (), 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 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.