sealing off of West Berlin from East Berlin by the Berlin Wall the entrances of the stations on these lines located in East Berlin were shut. However, western trains were allowed to continue to pass through without stopping. Passengers of these trains experienced the empty and barely lit ghost stations where time had stood still since 13 August 1961. West Berlin's public transport operator BVG (West) paid the east an annual charge in Western Deutsche Marks for its underground lines to use the tunnels under East Berlin. U 6 and S 2 also had one subterranean stop at the Eastern Berlin Friedrichstraße railway station, the only station beneath East Berlin where western U Bahn trains were still allowed to stop. Passengers could change there between U 6, S 2 and the elevated S 3 (then starting and ending in Friedrichstraße) or for the transit trains to West Germany, buy duty-free tobacco and liquor for Western marks in GDR-run Intershop kiosks, or enter East Berlin through a checkpoint right in the station. See also Berlin Crisis of 1961 1986 West Berlin discotheque bombing Berlin Brigade History of Germany (1945–1990) Judgment in Berlin List of Commandants of Berlin Sectors List of divided cities RAF Gatow Spandau Prison Stunde Null United States Army Berlin Berlin Airlift Further reading Vysotsky, Viktor. West Berlin. Moscow: Progress Publishers. 1974. References External links Berlin 1969 in the forgotten midpoint of the Cold War...twenty years after the Berlin Blockade...twenty years before the fall of the Berlin Wall Berlin Exclaves History of the Western Allies in Berlin City-states Berlin, West Former enclaves Former republics States and territories established in 1949 West Germany 1949 establishments in West Germany 1990 disestablishments in West Germany