page_title: U6 (Berlin U-Bahn)
section_title: Beginnings
hierarchical_section_title: U6 (Berlin U-Bahn) / History / Beginnings
caption_attribution_description: English: Map of the former "North South Underground Line" in Berlin, stations and names of 1930Deutsch: Die Nord-Süd-U-Bahn der Berliner U-Bahn mit Namen und der Strecke von 1930
context_page_description: U6 is a Berlin U-Bahn line, 19.9 km long line with 29 stations. It runs in a north-south direction from the Berlin locality of Tegel in the north via Friedrichstraße to Mariendorf, a locality in the southern part of the city. It is a so-called large profile line.
  During the Cold War, both U6 termini were in the former West Berlin but the line passed under East Berlin for a short section of its route. Five of its stations were sealed off by East German authorities and the trains went through these so-called “ghost stations” without stopping, while a sixth, Friedrichstraße, remained open primarily as a transfer station between the U6 and the S-Bahn lines using the north-south S-Bahn tunnel, but also as an official border crossing between East and West Berlin.
  It was formerly named "Cᴵ" from 1923 to 1928.
context_section_description: As early as 1901 the city of Berlin had plans for a subway running from north to south under Friedrichstraße. Werner von Siemens also had plans for a line under that impressive street, but at the time the city decided the transport system should be in public hands and began construction of the so-called North-South Line from Wedding to Tempelhof, with a branch to Neukölln. This work was delayed and finally abandoned due to difficulties associated with World War I. Relics of this early phase up to 1918 can still be found in the rolled-steel support pillars at the Oranienburger Tor station, still bearing the trade name of the supplying rolling mill, Rombach in Alsace-Lorraine.
  In 1919 work was resumed, but during the post-war hyperinflation period the filling in of the already existing tunnel was proposed in 1921. However it was decided to continued construction after all, and on 30 January 1923 the first tunnel section was opened between Hallesches Tor and Stettiner Bahnhof (the latter going by the name of Naturkundemuseum station since 13 December 2009, replacing the name Zinnowitzer Straße station). A northwest extension was opened on 8 March 1923 between Stettiner Bahnhof and Seestraße, with a maintenance workshop being built at the Seestraße station.
  At the junction Mohrenstraße and Friedrichstraße two subway lines intersected for the first time: the city’s North-South Line, renamed Line C, and the private Central Line (Centrumsline). But as the concept of a tower station (accommodating two lines stacked one above the other) was not well known, the city of Berlin built its own station, named Leipziger Straße (now Stadtmitte),160 meters from the Central Line station. The result is that passengers transferring between the two lines still today have to walk through a long connecting pedestrian tunnel, popularly known by Berliners as the “mouse route” ("Mäusetunnel").
  At Belle-Alliance Straße (now named Mehringdamm) where the line separated into two branches, three tracks were built. From the western track (side platform), trains ran to both termini, Tempelhof and Neukölln; the central platform was used for trains heading downtown, the middle track for those coming from Neukölln and the eastern track for trains coming from Tempelhof. In the course of constructing the U7 line, the station was completely redesigned and is now called Mehringdamm.
  Due to disputes with the administrative district of Tempelhof, the first route to be built was the branch to Neukölln. Work on the other branch only began in 1924, but just two years later, on 14 February 1926, the stretch from Belle-Alliance-Straße to Kreuzberg (now the Platz der Luftbrücke station) was opened. A year later this second branch extended to Tempelhof Airport (now the Paradestraße station). This now-closed airport was located to the east of the U6 track.
  In 1929 the line was extended to intersect with the S-Bahn’s Tempelhof station on the circle line (Ringbahn). A large ticket hall was erected for both S- and U-Bahn passengers. Since the station had to be built very deep to accommodate the subway line, there was room for a spacious ticket hall.
caption: The North-South line (now U6/U7) showing its name and extent in 1930
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