Bunker Fuchsbau, Military bunker in Fürstenwalde/Spree, Germany.

Bunker Fuchsbau is an underground military facility in Fürstenwalde with multiple levels designed to shelter hundreds of soldiers during wartime operations. The complex contains command centers, technical installations, and working areas that visitors can explore today.

The old section was built from 1942 over former lignite mine tunnels, using 900 prisoners per twelve-hour shift from the Sachsenhausen subcamp Fuchsbau, under the secret "Amt für Wellenausbreitung". From 1944 it handled communications for the SS Führungshauptamt and the OKW at Zossen under the code name "Hegewald". From 1965 to 1990 it was the Central Component Headquarters 14 of the East German air force, then served the Bundeswehr's 5. Luftwaffendivision until December 1994.

The site presents three different periods through its exhibitions: Nazi Germany, East German military operations, and the unified German state after 1990. Visitors can see how successive military forces adapted the same spaces to their own needs.

The site is run by volunteers as the Bunkermuseum Fuchsbau, with guided tours held weekly. The complex lies in the Rauensche Berge south of Fürstenwalde, about 55 km east of Berlin, and covers roughly 40 hectares. Visitors are shown the current air situation within a radius of about 250 km, archive displays from 1988, and working telephone and telex connections.

The bunker's command post displayed live air situation data for a radius of about 250 km, and tours still show archived air plots from 1988 plus working telephone and telex connections. The site also preserves equipment for air traffic control and air situation display, which is why it is protected as a technical monument.