Hitler were there in 1943-1944. The Place called "Wilczy Szaniec"( Wolfsschanze)
Very interessant place, if you visit Poland you must come here
https://en.wikipedia.org/wiki/Wolf%27s_Lair
In July 1944 Claus von Stauffenberg attempt to kill Hitler. He made a briefcase bomb and bring it to a daily conference room. After detonation room was destroy but Hitler was only a little bit injured.
After war it took until 1955 to clear all 54,000 land mine around object