A Nazi academy designed by Albert Speer and forgotten for decades has become the focus of a monumental treasure hunt in Berlin after explorers claim to have found it buried under a mountain of rubble.
The huge complex, which was part of Speer's grand design for the Third Reich's capital Germania, was intended to train a new generation of Nazi military engineers producing “wonder weapons”.
Hitler laid the foundation stone in 1937, but building was halted three years later as fighting in the Second World War escalated.
After the Allied victory in 1945, Britain considered using the building as its Berlin headquarters, but converting it proved too complicated and the idea was dropped.
The site, to the southwest of central Berlin, was then chosen as a dumping ground for wartime rubble from the shattered city.
The original 50 metre (115ft) high plateau, on which Speer had intended an academic “city”, was transformed into a 114 metre (350 feet) high mini-mountain known as “Devil's Hill”. Despite its name, the area -subsequently became a favourite with German hikers and kite-flyers.
Soon all memory of the academy, whose initial budget was 80 million reichmarks and was designed with a bunker to hold 5,000 people, was buried under 40 million tons of debris.
“It was forgotten,” said Sascha Keil, a spokesman for the group Unterwelten, or Underworlds, which has specialised in digging out Berlin's buried history. He said that the academy had been “80 per cent ready” before work was halted. Despite being partially stripped for building materials after the war, the bulk of it remains entombed.
“We are particularly interested in the large underground network of the academy,” said Mr Keil. “We have conducted a geological survey but the only way to be sure exactly what is there is to dig.”
Berlin municipality, already burdened by huge debt, has proved unwilling to excavate the city's notorious past. “They don't want know,” said Mr Keil. “They didn't even want to mark the Fuhrer Bunker [where Hitler spent his final days in 1945]. We did that at our own expense.”
From small beginnings 10 years ago, Unterwelten has become a well-respected, well-staffed authority on Berlin's vast trove of subterranean secrets.
It has succeeded, often by torchlight and on hands and knees, in unveiling huge tunnel networks and air-raid shelters which have been bricked up, buried or bombed.
With its guides, tens of thousands of visitors have seen relics of the Nazi era that German authorities are either not rich enough, or not comfortable enough, to put on public display.
”They do not want to show people, for example, where Hitler and Eva Braun's bodies were burned,
” said Mr Keil.
But Unterwelten's underground discoveries are not limited to the Second World War era.
In its initial perusal of the Devil's Hill, it has chanced across one tunnel linked to the Cold War-era Allied listening post that was eventually built on Speer's academy and the mound of rubble above.
“It emerges 300 metres away from the hill in the forest,” said Mr Keil. “We think it was an escape route for allied soldiers from the listening post in the event of a sudden Russian attack.
“But,” he added, “that's another story.”