Also called the Wolf's lair, it's a fortress complex deep in the woodlands of northeastern Poland that served as one of Hitler's secret military headquarters during World War Two and was destroyed by the Nazi forces as they retreated in early 1945. It's also the site of an assassination attempt on Hitler by Colonel Claus von Stauffenberg which was popularised by a 2008 film starring Tom Cruise.

The site -- whose name refers to Hitler's nickname, "Mr. Wolf" - consisted of 80 buildings at its peak.

Poland is looking for an investor to turn the "Wolf's lair" of Nazi leader Adolf Hitler into a major tourist attraction.