A tour of a Soviet era nuclear bunker targeting the West
30 December 2012 Last updated at 08:53 GMT
Only now are Germans learning the full extent of their past when the East was ruled by the Soviet Union.
North of Berlin, for example, there is a hidden nuclear base about which the East German government itself had little knowledge.
In 1959, though, nuclear missiles were stationed there, targeted at Western Europe.
BBC correspondent Steve Evans has this guided tour.