The mystery of Russia's famed Amber Room, seized as the spoils of war by the Nazis, has puzzled historians and experts since it disappeared in 1945.
Sergei Trifonov, however, believes he has solved the riddle, and that the treasure – ornately carved panels of glowing amber, formed from fossilised resin – lies underneath a bunker in the Russian enclave of Kaliningrad.
"Believe me or not, it's there, 12 metres down in the sub-soil," he said, pointing to the entrance of a bunker that sheltered the Nazi high command in the last hours of the Battle of Koenigsberg.
"This place was built [in February 1945] with two aims: accommodating the headquarters of General Otto Lasch and storing the treasures of Koenigsberg, a city under siege," argued the historian-turned-journalist -and-lecturer.
Koenigsberg, in what was then German East Prussia, is now Kaliningrad, the capital of Russia's westernmost region of the same name.
The Nazis removed the treasure from a palace that once belonged to empress Catherine the Great outside Saint Petersburg after invading the Soviet Union in 1941.
Once hailed as the eighth wonder of the world, the trophy was brought here and stored in the former castle of the Teutonic Knights in the centre of the city.
But its subsequent fate remains unknown amid the turmoil of war and heavy bombardment of the city by the Allies.
The Red Army seized the ruined city on 9 April, 1945. Stalin triumphantly annexed it and renamed it Kaliningrad, after a leader of the Supreme Soviet.
The Amber Room – with its 35 square metres of panelling – was sighted in the last month of the final attack, after it had been disassembled and stored in cases.
After that, it vanished.
There are many theories about what happened next. The panels may have been destroyed by bombs, secretly moved to Germany or hidden in the maze of tunnels under Kaliningrad.
To test his theory, Trifonov has begun to probe the soil under the bunker using a ground-penetrating radar, and pump out water. He has already unearthed a brick-lined room.
The bunker is 300 metres from the site of the castle – demolished in 1967 – that sheltered the Amber Room. Its iron gate features Viking symbols and a Teutonic cross, suggesting it wasn't only for military use, Trifonov argues.
"I'm sure that the Amber Room wasn't taken away. The theory that it is now in Germany doesn't make sense," he said.
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