U-Boot Bunker Valentin

A cycle tour brought me along the River Weser, roundabout 30 miles from Bremen, to the U-Boot Bunker Valentin.
The construction started 1943. Up to 10 000 forced labourer worked on it - more then 1200 of them died between 1943 and 1945.
The British Royal Airforce bombed the building in 1945, some years the bunker was used for bomb testing. After that children used it as playground until the German armed forces started to store spare parts in the remains.
Since 2010 is it planned to develop the bunker into a memorial place. Here is the homepage.