Prisoners from across Europe poured concrete roofs several metres thick on the banks of the Weser. Two bombs from the Dambusters' squadron went through one of them, and no submarine ever left the building.
An earth dam with a concrete heart that survived the bouncing bombs in 1943, a Tallboy in 1944 and, in 1959, a live five-tonne bomb found at the bottom of its drained lake.
A Kaiser-era dam in the hills of Hesse, three villages beneath its lake and a gap blasted open in the early hours of 17 May 1943.
A Kaiser-era wall of quarry stone that held back the Ruhr's water for 30 years, was breached in minutes on 17 May 1943 and was closed again within four months.
Nineteen Lancasters, a bomb that bounced across the water and one night in May 1943: how 617 Squadron breached the Möhne and Eder dams, and what the raid really achieved.
