The Government Bunker (Regierungsbunker) in Germany, officially named Ausweichsitz der Verfassungsorgane des Bundes im Krisen- und Verteidigungsfall zur Wahrung von deren Funktionstüchtigkeit (AdVB), in English: "Emergency Seat of the Federal Constitutional Organs for the State of Crisis or State of Defence to Maintain their Ability to Function" was a massive underground complex built during the Cold War era to house the German government, parliament and enough federal personnel needed to keep the government working in the event of war or severe crisis. Located only about 25 kilometres (16 mi) south of Bonn, Germany, in the Ahr Valley between the towns of Ahrweiler and Dernau, it was one of the best kept secrets of West Germany. It was built between 1960 and 1972 inside two abandoned railway tunnels that were built as part of the Strategic Railway, maintained and kept in a working condition for about 30 years and decommissioned in 1997. A small part of the once-secret site is now open to the public as Government Bunker Documentation Site, while the vast majority is abandoned and sealed.

The Ahr valley is named after the Ahr, a left tributary of the Rhine in Germany. It begins at the Ahr spring (Ahrquelle) in Blankenheim in the county of Euskirchen and runs generally eastwards. At its southernmost point it enters the county of Ahrweiler, and hence the state of Rhineland-Palatinate. Running through the collective municipality of Adenau the valley bends northeast at its confluence with the Adenauer Bach and reaches the collective municipality of Altenahr, from where it resumes its characteristic west to east course, albeit interrupted by meanders. Here begins the section that is known as the Ahr valley (Ahrtal) in a touristic sense. Here it is characterized by vineyards on the south-facing slopes and a picturesque rocky landscape, carved out by the river creating a 300 metre deep gorge in the Ahr Hills. In the next stage the Ahr reaches the area of the county town of Bad Neuenahr-Ahrweiler, before finally discharging into the Rhine south of Remagen in the borough of Sinzig.