Until 1923 the station was known as Leipziger Platz. From then the name was Potsdamer Platz. The station was closed from 13 August 1961 to 13 November 1993 when Berlin was separated by Berlin Wall. A border fortification was placed near to Potsdamer Platz station. This border fortification was removed in December 1990. It was imagined that trains on either side would simply run as far as the last stop before the border and then reverse back. This was partly the case with the U-Bahn line through Potsdamer Platz, as the Mohrenstraße in October 1991, operationally became a terminus for trains on the eastern side. On the western side however, the entire section all the way back to Wittenbergplatz was closed completely and at least partially dismantled. Indeed, two of the abandoned stations on this section, Bülowstraße and Nollendorfplatz, were converted into markets. The antiques market at the latter was housed in sixteen old wooden coaches lined up beside the platforms, while another coach even carried passengers back and forth to Bülowstraße where a Turkish bazaar was sited. This station was intended to be an interchange with the future driverless line U3 and U10, however the plans were scrapped when the U3 is primarily used since December 2004. It was partially converted into the event space for events and exhibitions since 2006. In the latter years of the Wall's existence, part of the abandoned U-Bahn section, the stretch between Gleisdreieck and Potsdamer Platz, had actually been utilised by another line - the M-Bahn (Magnetic Levitation Railway) which, instead of diving underground as before, once it had crossed over the Landwehrkanal, remained above ground on a lengthy elevated structure supported on steel columns, which curved across the Potsdamer Bahnhof's former site to end at a terminus of its own at Kemper Platz, very near the Philharmonie (Philharmonic Hall, home of the Berlin Philharmonic Orchestra). As early as the late 1970s the West Berlin government had discussed introducing such a system to the city, particularly a section linking Tegel Airport with the centre. The go-ahead was finally given for the building of a test track at Potsdamer Platz on 2 December 1980, with a ground-breaking ceremony taking place on 16 June 1983, construction starting in earnest in December 1983 and the first test runs occurring in June 1984.