One hundred and seventy-three underground stations dot the cityscape, and building work is always going on somewhere. Alongside improvement work at many locations, closing the gap between Alexanderplatz and Brandenburger Tor on the U5 is currently the largest project underway. The history of Berlin’s underground is marked by three major stages of development, each of which expanded the network.

the three stages of development on the underground

The “founding line” was built during the first stage from 1902 until the start of the First World War in 1914. To the present day, most of this line actually runs overground on an elevated railway. Between Warschauer Brücke and Gleisdreieck, the U1 runs along a viaduct above the road and the Landwehr Canal, only descending underground shortly before reaching Kurfürstenstraße station. The second major construction project in the first stage of development was today’s U3 which connects Dahlem with Nollendorfplatz and back then continued on the present U2 line to Alexanderplatz. Work to complete the U3 and U4 also began before the First World War; these were prestigious projects undertaken by what at the time were the independent towns of Charlottenburg and Schöneberg.
During the second stage of development between the wars, work focussed on building the inner-city sections of the wide gauge network on today’s U5 and U9 lines.
The third stage began in earnest in 1953. In the west part of Berlin, work continued at both ends of lines U7 and U9, while the U6 was extended to the north. In the east, the U5 was extended towards Hönow. 

An array of prestigious architects were involved in the design and construction of Berlin’s underground stations. Two of them, however, stand head and shoulders above the rest: Alfred Grenander in the first and second stages of development, and Rainer G. Rümmler in the third.

Alfred Grenander

The Swedish architect Alfred Grenander (1863–1931) was involved in planning and building Berlin’s underground stations from the very beginning. His three major works are the conversion of Wittenbergplatz underground station in 1913, the creation of a monumental station at Hermannplatz with a direct link to the Karstadt department store and Alexanderplatz station with its three subsurface levels. Grenander had a stunningly simple idea to aid passengers: he designed his stations with “identifying colours” which set them apart from the others on the same line. This means just a brief glance is necessary for passengers to know where they are. Other outstanding underground stations by Alfred Grenander: Stadtmitte (U2), Südstern, Platz der Luftbrücke, Märkisches Museum, Rosa-Luxemburg-Platz.

Rainer G. Rümmler

Rainer G. Rümmler (1929–2004) is considered the leading architect of the third stage of development in West Berlin after the Second World War. All the stations on the western extension of the U7 from Möckernbrücke to Rathaus Spandau from the 1970s and 80s were designed at his drawing board. Rümmler retained Grenander’s principle of “identifying colours” and expanded it by incorporating a play on names: to give just a few examples, the green walls at Eisenacher Straße station are a reference to the Thuringian forests (where Eisenach is located), Bayerischer Platz is decorated in white and blue (the colours of Bavaria) and stars shine from the ceiling at Paulsternstraße (“Stern” = “star”). Rümmler was also responsible for the extension of the U7 to Rudow and many stations on the U9 and U8. 

A number of underground stations have intriguing features: Rathaus Steglitz, Schloßstraße, Walther-Schreiber-Platz, Innsbrucker Platz and Kleistpark stations were all built as four-track interchanges in preparation for the once-planned U10. Jungfernheide underground station also has four tracks. In former plans, the extension of the U5 would pass through here. Until 1970, a short line ran from today’s Deutsche Oper station, which also had four tracks, to Richard-Wagner-Platz. This branch became superfluous when the U7 was extended to Spandau. It is, however, still used for service purposes.