Felsennest, which translated to the "eyrie on the cliffs", was the codename for Adolf Hitler's command bunker from which he oversaw the Blitzkrieg campaign against the Western Allies in Europe in May 1940. Blasted from the rock of a wooded mountaintop, Felsennest was located near the village of Rodert and the ancient German city of Aachen.
In late May, Felsennest was the scene of the Seventh Doctor's confrontation with Hitler. The Doctor freed the Timewyrm from Hitler's mind and subsequently convinced him to let the British Army escape destruction at Dunkirk. Hitler issued orders to that effect to General Heinz Guderian's forces, changing the course of World War II. (PROSE: Timewyrm: Exodus)