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Origin and history

The dome of Helfaut-Wizernes, nicknamed Bauvorhaben 21 or Schotterwerk Nordwest, was built between 1943 and 1944 by Nazi Germany as a launch base for V2 rockets targeting London. Located in an old chalk quarry near Saint-Omer (Pas-de-Calais), it included a 71 m diameter concrete dome, 5 m thick, and a 7 km network of tunnels housing workshops, warehouses and a liquid oxygen plant. Designed to launch dozens of daily missiles, it was sabotaged by the Allied bombings (Operation Crossbow), notably via Tallboy bombs in 1944, preventing its completion.

The complex, supervised by the Todt Organisation and companies like Philipp Holzmann A.G., employed 1,400 workers in 1944, including French requisitioned (STO) and Soviet prisoners. Despite its resistance — a single bomb reached the dome — the landslides caused by the raids blocked access. Abandoned in September 1944 after liberation, the dome was partially destroyed on Churchill's orders to avoid military reuse. It remained abandoned until the 1990s.

Turned into a museum in 1997 (La Coupole), the site offers exhibitions on the occupation, German weapons (V1, V2) and space history, with original pieces like a V2 loaned by the Smithsonian Institution. A memorial honours the 8,000 shot and deported from Nord-Pas-de-Calais. The museum, which attracts 120,000 visitors annually, has included a planetarium since 2012. It also manages the site of Mimoyecques V3 gun, linked to this complex.

The bunker's design reflected tensions between German engineers: some advocated mobile sites (Meillerwagen), but Hitler imposed monumental structures like Watten, a target of the Allies in 1943. The choice of Helfaut was motivated by its proximity to the railway (line Boulogne-Saint-Omer) and its chalk career, ideal for digging tunnels and underground rooms. The project, estimated at one million tons of concrete, became obsolete after the Disembarkation, with the Nazis favouring mobile launches from forests.

The postwar period saw the site studied by the British Crossbow Committee, which saw a potential for missiles much larger than the V2 (such as Project A10). Ranked dangerous in 1945 due to collapses, it was returned to its private owner. In the 1980s, exceptional excavations and openings (as in 1987, with 20,000 visitors) revived historical interest. Public funding (state, region, EU) allowed its rehabilitation, revealing remains such as the Decauville rails or the unfinished 41 m diameter hexagonal hall.

Future

The site remained abandoned until the mid-1990s. In 1997, it was transformed into a museum and opened to the public.

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