The Dome (La Coupole d'Helfaut-Wizernes)

 museum, Second World War 1939-1945, astronomy, planetarium, fortification, bunker

After the bombing and serious damage at the Watten bunker site, the Organisation Todt looked at an alternative place for a protected V2 base. Wizernes-Helfaut is south of Saint-Omer. Construction started in July 1943, the first Allied bombing took place in March 1944. The site was protected by an enormous bombproof concrete roof (dome shape) weighing 45,000 tons, 71 meters in diameter and 5 meters thick, built over a chalk quarry. The roof could withstand even the heaviest Allied "Tallboy" bombs (6 tons). A 7 kilometers tunnel complex was built in the quarry walls. A railway took the rockets in the tunnel, where they were stored and prepared for launching. Due to the height of the inside, complicated lifting gear was unnecessary. The rockets were to be launched outside on two launching pads (called Gustav and Gretchen). The walls of these pads can still be evidenced today, notwithstanding the heavy Allied bombing. The site was eventually abandoned as a rocket base in August 1944, mainly as a result of the huge damage to the outside communication lines (roads, railway) which made further construction almost impossible. The amount of actual damage inflicted to the site was, however, limited. The dome as well as the tunnel vent and part of the tunnels remained largely undamaged. After the site had been left, all plans for hardened V2 launching sites were abandoned and deployment was shifted exclusively to mobile launchers (called Meilerwagen).
The site has nowadays been turned into a museum. One can enter the main tunnel, take the elevator to the upper floor just under the concrete roof (where a rare genuine V2 rocket is on display, as well as an excellent exhibition on the German secret weapons which ultimately led to Man's conquest of space), and go down via the area at the base of the site where the V2 rockets were prepared for launching. A worthwhile visit. Beware, however, that the inside temperature in the tunnels is only 7° C and slightly more just under the roof. Jackets are available at the entrance.

More information can be found at this very informative site and at the official site of "La Coupole". www.lacoupole-france.com/en/