London, Mar.19 : Dank and dark, built by slave labourers, the vast concrete complex known as Valentin on the north German coast was once Germany's notorious submarine factory.
Now, this largest surviving bunker of the Third Reich is up for sale to anyone interested.
The place has become a millstone around the German Government's neck, as its upkeep swallows up to 800,000 (£630,000) a year from the Defence Ministry budget, The Telegraph reports.
"And that's just the absolutely essential investments needed to stop the place crumbling," says Commandant Wolfgang zu Putlitz, who is in charge of guarding and maintaining the site.
Hitler, concerned that Germany was losing the edge in the war for the sea-lanes, ordered the construction of the factory near Bremen with the aim of producing a new U-boat, the sophisticated XXI model, every 56 hours.
Germany had wreaked havoc on Allied shipping at the beginning of the war with a fleet of only 57 submarines. By June 1943 the tide was turning: the Allies had developed accurate detection devices that could outwit and trap the expanded U-boat force.
The factory, codenamed Valentin, was Hitler's last chance to stop the Allies ferrying supplies and reinforcements by sea. It was to be shielded from bombing raids by a bunker with a thick pre-stressed concrete roof.
The result was a silo with the dimensions of a cathedral: 426m (1,400ft) long, 97m wide, 25m high. At one end was a diving basin for the last tests on the U-boats before they would slide into the Weser river and head for the North Sea.
In the event, no submarine left the factory. By March 1945 the factory, begun 18 months earlier, was 80 per cent complete. Then a British Bomber Command raid succeeded in penetrating the roof. Barely a month later, before repairs were complete, the war was over.
The initial idea after the war was to blow up Valentin, but that would have required at least 500 tonnes of explosives and the blast would have wiped out most of the neighbourhood. So it was taken over by the German Army, which has been using part of it as a storehouse.
Blowing it up is now out of the question because it has been officially listed.