The bunker complex at Gierłoż, near the town of Kętrzyn in Poland’s northeastern Mazuria region, was where the Nazi dictator spent much of the war, devising plans that determined the fate of nations and affected millions.
The complex, tucked away in a forest and known as the Wolfsschanze, or Wolf's Lair, was Hitler's Eastern front military headquarters from June 1941 to November 1944. It was located in what used to be Germany’s East Prussia region, and is now northeastern Poland.
The site was where Hitler conferred with top Nazi dignitaries and received visits from foreign leaders. It was also where he came up with plans to use prisoners in the German arms industry and issued orders to build new death camps, according to historians.
More than 2,000 people lived and worked at the Wolf's Lair at one point in 1944. These included members of Hitler's inner circle, such as Hermann Göring, Heinrich Himmler, Martin Bormann, Wilhelm Keitel and Joseph Goebbels.
In January 1945, the bunker complex was blown up and abandoned by the Germans hours before the arrival of advancing Soviet troops.
The Wolf's Lair, called Wilczy Szaniec in Polish, last year attracted some 70,000 visitors a month, according to Poland's PAP news agency.
One of the priorities of the makeover effort has been to recreate the interior of a wooden barrack where German Colonel Claus von Stauffenberg attempted to kill Hitler 75 years ago this month—on July 20, 1944.
Stauffenberg used a briefcase bomb that killed four Nazi officers, but Hitler survived with only slight injuries.
The story is depicted in Valkyrie, a 2008 Hollywood movie starring Tom Cruise.