The Felsennest was the codename for one of several Führer Headquarters used by Adolf Hitler during the course of World War II.
It was located near Bad Münstereifel, in the western part of Germany. It was much more cramped than Hitler's other headquarters, having only four rooms. Hitler was at the Felsennest in the autumn of 1939, because there were plans to invade France and the Low Countries. He was there again on May 10, 1940 when the invasion took place.
Groß, Manfred: Bunkerstellungen der Luftverteidigungszone West im Rheinland und Hitlers Hauptquartier in Bad Münstereifel-Rodert. Verlag Werner Sünkel, Offenhausen 2001. ISBN 3-930060-90-6.
Wikipedia https://en.wikipedia.org/wiki/Felsennest
Address (Unnamed Road), 53902, Germany
Coordinates 50°32'54.312" N 6°46'15.791" E