For more than half a century the grey cliffs of an old chalk quarry in north France have hidden a grim secret. From the road leading to the village of Wizernes, near Saint-Omer, the only indication of anything unusual is the top of a concrete dome poking through the bushes and trees that overgrow the slopes - all that is visible of a vast underground bunker built under orders from Hitler to launch V2 rockets at London.

Now this subterranean silo has become an extraordinary museum. La Coupole is within easy reach of the Channel ports, five kilometres from Saint-Omer. A decade ago its founders decided it should be restored and used to teach young Europeans about the atrocities of the Second World War and the more peaceful conquest of space which emerged from that past. Described as a History Centre of War and Rockets it opened earlier this year, financed jointly by France and the European Union and run by the Pas-de-Calais departmental council.

Education is paramount. The centre co-operates closely with the French ministry of education and programmes are devised with school groups in mind. Films are 20 minutes long at most. Some of the material could be disturbing to small children and the visit is recommended for over-11s.

With infra-red headsets relaying commentaries in English, French, Dutch or German, visitors wander through parts of a 7-kilometre maze of cold, dripping, gloomy railway tunnels, passages and galleries, all preserved in their original state. A lift takes them to the exhibition area within the dome, with its cinemas, slide shows, displays, models and exhibits including old V2s and V1s - doodlebugs, as Londoners called them. (The V stands for Vergeltungswaffe: revenge weapon.) Here is traced the horrific story of the Nazi missile programme both in Germany and in this region of what was occupied France, and its sequel after the war when the technology was used to land men on the Moon.

Visitors learn of early German enthusiasm for rocketry, Hitler’s appropriation of the technology for military use and the construction of Peenemuende, the secret research base in the Baltic where 2,000 engineers and technicians developed the V2. Designer Wernher von Braun took only three years to produce the 14-metre high strategic rocket, the first-ever electronic guidance system.

With Nazi defeats in 1942-43, perfection of the rocket took priority. As well as mobile launch sites, the Germans built colossal bunkers along the occupied Channel coast. After Allied bombardments, Hitler ordered construction of an indestructible bunker in the chalk cliffs near Saint-Omer to store and launch his secret weapon. The Todt organisation, responsible for all Nazi building works, created the enormous hilltop dome - five metres thick and 72 metres across - to protect the underground base from bombs. Among the work-force were Russian and Polish prisoners, including women, who were treated atrociously.

V2 manufacture now started in earnest at Dora-Nordhausen in Germany with a concentration camp workforce of 32,000 Russians, Poles, French, Belgians, Czechs and political prisoners who bored two tunnels to install production lines.

Marcel Petit, a French survivor of Dora, is quoted in one of the films: “Two rows of SS guarded the entrance, shrieking so loudly and lashing out with such ferocity that they were like demons. It really was the gates to hell. To get through the bottleneck the mass thrust, stretched, cowered and flinched as truncheons came down on skulls and thudded on backs and shoulders . . . Grey-faced prisoners were everywhere, miserable worms carted rubble and bags of cement . . . Near the door of the gallery where we slept were the night’s corpses, dragged out of the blocks feet-first.”

The V2s and V1s killed 20,000, mostly in London and Antwerp; but La Coupole was abandoned before completion and no missiles ever went there. If the Nazis had not retreated in summer 1944, they could have been firing 50 V2s daily at London within three months.

Exhibits also cover the Nazi occupation, Jewish deportations and French Resistance of northern France and the horrific evacuation of Dora-Nordhausen. Then the story continues post war to reveal how German engineers and scientists were snapped up by the United States, the Soviet Union and France, all determined to succeed in the rocket race.

A film shows a smiling von Braun surrendering to the Americans. He went on to play a leading role in developing the US space programme, including the Apollo Moon landing project, the climax of the permanent exhibition.

La Coupole, BP 284, 62504 Saint-Omer. Tel: 00 33-3 21 93 07 07. Fax 00 33-3 21 39 21 45. Disabled access. Book groups