Wikipedia
Tränenpalast
The Tränenpalast is the Berlin colloquialism for the former border crossing at Berlin Friedrichstraße station, where East Germans said goodbye to visitors going back to West Germany. From 1962 to 1989 it was the border crossing for travellers by S-bahn, U-bahn and train between East and West Germany. It was used only for westbound border crossings, with separate checkpoints for West Berliners, West Germans, foreigners, diplomats, transit travellers and East Germans.
The term derives from the tearful goodbyes that took place in front of the building, where western visitors had to say farewell to East Germans that were not permitted to travel to West Berlin.