A massive WWII German bunker complex located near Saint-Omer in the Pas-de-Calais department of northern France, La Coupole was originally codenamed Bauvorhaben 21 ('Building Project 21') and intended as a launch site for V-2 rockets against Allied targets. Constructed by forced labor under the supervision of the Organisation Todt, the structure features a colossal reinforced concrete dome—over 70 meters in diameter and up to 12 meters thick—designed to protect the facility from aerial bombardment. Its scale and engineering reflect the Nazi regime’s ambition to wage long-range terror warfare, making it one of the most formidable bunker complexes of the Atlantic Wall.
The site was never completed as a launch facility; Allied bombing in 1944 rendered the internal infrastructure unusable before operational deployment. After the war, the structure was repurposed for industrial use, including gravel processing, before being acquired by the French state. Today, it houses the Centre d'Histoire de la Résistance et de la Déportation—a museum dedicated to the history of the V-2 program, forced labor, and the broader context of Nazi occupation in France.
Architecturally, La Coupole remains one of the largest surviving concrete fortifications from WWII, with its cavernous interior, rail systems, and fuel storage areas still visible. It stands as a powerful monument to both technological ambition and human cost, drawing visitors interested in military history, urbex, and Cold War-era fortifications. The site is fully accessible to the public and serves as an educational center for understanding the scale of Nazi infrastructure projects in occupied Europe.
Its location, approximately 5 km from Saint-Omer and 14 km southeast of Helfaut, places it within the historically contested Pas-de-Calais region—a key corridor for German defensive and offensive operations during the war. The bunker’s preservation ensures its role as a primary reference point for researchers and historians studying WWII bunker systems and occupation-era engineering.