Wolf's lair

The Wolf's Lair (Wolfsschanze in German) was a military headquarter of Adolf Hitler during World War II. It is located near the village of Gierłoż, 8km east of Kętrzyn in northeastern Poland.
Built between 1940 and 1941 by 3000 German workers, it consisted of 80 structures including 7 bomb-proof bunkers spread over an area of 18 hectares. It was here that the assassination attempt against Hitler took place in July 1944. The complex was blown up by the Germans in January 1945, as they retreated from the invading Soviet army.
Nowadays the compound is an open-air museum with ruins spread over the forest. From the parking it is possible to visit a section of the Wolf's Lair in 2-3 hours, walking on a number of trails.
How to get to the Wolf's Lair
The Wolf's Lair is best visited by car. The closest airport is the one in Olsztyn, which has flights to a few European cities.
Accommodation
There is a hotel immediately at the site, more in the region around it, all bookable via the international booking portals.