If these rock walls could talk, they might tell us how this site once served as a backdrop for some of the most horrific events of World War II.
The tunnel belongs to the bunker complex of the Dokumentation Obersalzberg, a museum at the Obersalzberg resort in southern Germany.
But, it is better known as having been part of the underground network that was built when Adolf Hitler turned the remote alpine village of Obersalzberg into his holiday retreat in the 1930s.
The area gradually became a second centre of power alongside Berlin. Important political decisions were planned and taken here, explains the museums's website, including those about the war and the Holocaust.
Today, the museum is a valued centre of learning, where visitors can delve into the history of Nazi Germany through its collection of documents, photographs, audio clips, maps and films.