The (formerly) stashed billions of the Bundesbank

Disguised as a school and recreation home of the Bundesbank, Germany's central bank, the bunker was built between 1962 and 1964 under a 8,700 square-meter (93,647 square-foot) plot of land in a residential area in Cochem in the state of Rhineland-Palatinate. The population suspected that there was a bunker, but the purpose of the facility was completely unknown even to direct neighbors.

The location was deliberately chosen at the time: It was hoped that the Moselle Valley would provide good protection against a nuclear blast wave. Up to DM15 billion (€7.6 billion at today's rate) of a secret emergency currency was stored in the then top-secret facility.

During the Cold War, the federal government feared that counterfeit money would be smuggled into the country in large quantities. The consequences would have been devastating: If confidence in the deutsche mark was lost, the entire national economy could collapse. It was therefore decided to print a parallel substitute currency — the BBK II.

The vault itself could only be entered by a few Bundesbank employees. The combination and key were stored in Frankfurt am Main. For protection, sensors were installed in the walls that reacted to noise and vibrations. When an alarm was triggered, the local police were automatically notified, but they also did not know what was in the bunker.

Around 15 billion of this secret currency were stored in boxes in the bunker in Cochem in small bills of 10, 20, 50 and 100 deutsche marks. In an emergency, the old deutsche mark bills would have been withdrawn and the replacement series issued. Every three months, employees of the Bundesbank from Frankfurt randomly checked the stocks.

Not only the money would have been safe in Cochem: In the event of a nuclear war, it would have been possible to survive for two weeks in the bunker in Cochem. There was a direct radio link to the Federal Interior Ministry in Bonn, diesel generators for electricity, 18,000 liters (4,755 US gallons) of fuel reserve and a deep well with a 40,000-liter water tank to supply drinking water.

In case of an emergency, the bunker could have accommodated 80 civilians. There were sleeping rooms, work rooms and a sand filter, which was supposed to ensure the flow of fresh air. Unfortunately, there is no further information on which 80 people would have found shelter here in the event of a nuclear attack.

In 1988, it was decided to destroy the spare money, as the security features on the bills were no longer sufficient and the need for cash was no longer considered urgent due to electronic payment transactions. The bunker in Cochem initially stood empty. In 2014, it was sold to an investor and has been open to visitors since 2016.