Remote, hidden in dense forest, protected by nearby lakes and marshes - the Wolf's Lair in Poland was a secure headquarters for Adolf Hitler in World War Two.
So much so, that the National Socialist leader spent 850 days at the vast, secret complex in 1941-1944, before withdrawing to his Berlin bunker.
Now the Polish state's Srokowo Forest District, which manages the site, is giving the Wolf's Lair a big makeover to pull in more tourists.
The district's spokesman Sebastian Trapik told the BBC that the foresters were "making every effort" to maintain "due seriousness and respect for historical truth" at the crumbling complex.
But critics argue that insensitive "attractions", such as amateurish re-enactments with people wearing National Socialist uniforms, could turn it into a sort of "Disneyland".
All the Germans' reinforced concrete bunkers, minefields and camouflage were no protection against the traitor officers who tried to kill Hitler at the Wolf's Lair on 20 July 1944.
Hitler survived the briefcase bomb with only light injuries, mainly thanks to a massive oak conference table.
The bomb killed four - three of them officers - and injured more than 20. The German army plotters, led by Col Claus Schenk Graf von Stauffenberg, were quickly arrested and executed.
Mr Trapik says a "priority" at the site now is to reconstruct the scene of the bombing, including life-size "symbolic figures depicting those present at the time".
The National Socialists detonated massive explosive charges to demolish the dozens of bunkers and other installations as the Soviet Red Army advanced in January 1945.
For decades, in communist Poland, the forest grew back in the ruins and moss spread over the giant concrete blocks.
The site's managers are now improving tourist facilities, but such efforts would backfire if they encouraged National Socialist pilgrimages.
There are new information panels, a new car park and entrance building, and plans to build a hotel and restaurant.
A free app guides visitors round the site and they can watch a film about the National Socialist HQ's history. Some military equipment is also on show.
Nearly 300,000 tourists visit every year, most of them Poles and Germans. The basic entrance fee is 15 zloty (£3.16; $4).
Mr Trapik says there are plans for historical re-enactments, starting this summer with a staging of Operation "Ostra Brama", when the Polish Home Army defeated the German Wehrmacht in Vilnius in 1944.
That Polish victory was short-lived, as Soviet forces sweeping westward soon began imposing a communist terror.