It runs completely underground for a length of 31.8 kilometres (19.8 mi) through 40 stations and connects Spandau, via Neukölln, to Gropiusstadt and Rudow.

Starting in Rudow, at the junction of Gross-Ziethener Chaussee and Neuköllner Straße, the U7 runs northwest below the road Alt-Rudow, before bearing west in the Gropiusstadt area.

It continues north, crossing the urban motorway and the Ringbahn while under Karl-Marx-Straße, then heads north-west under Hasenheide, Südstern, and Gneisenaustraße until it reaches Mehringdamm after a very sharp right curve.

A curve into Wilmersdorfer Straße takes the U7 north to Bismarckstraße station, where it makes a further turn into Richard-Wagner-Straße, travelling under this road and its northern continuations Wintersteinstraße and Sömmeringstraße.

The U7 passes through 12 districts of Berlin: Rudow, Gropiusstadt, Britz, Neukölln, Kreuzberg, Schöneberg, Wilmersdorf, Charlottenburg, Charlottenburg-Nord, Siemensstadt, Haselhorst, and Spandau.

Around 1901, the city of Berlin planned to build an underground railway line below Friedrichstraße to connect the north to the south.

Werner von Siemens also had plans for a north–south line, under Nobelstraße, at the same time, but permission for these was declined on the grounds that public transport should be in municipal ownership.

The construction work was continued, however, and the first tunnel section from Hallesches Tor to Stettiner Bahnhof (later renamed Naturkundemuseum) was opened on 30 January 1923.

The history of the U7 began with the construction of the branch to Neukölln, when the stretch from Hallesches Tor to Gneisenaustraße was built; it opened on 9 April 1924.

The branch station Belle-Alliance-Straße (later renamed Mehringdamm), which opened in 1924, had three tracks: a connection to Tempelhof led from the first platform; to Neukölln from the second; and to the city centre from the third.

A separation of the Neuköllner branch from the North-South Line was decided upon in order to avoid an overload on the transfer station Hallesches Tor.

Feeder and distribution traffic, until 1967 by tram, replaced by several bus lines, provided solely for the development of Spandau on the subway station Ruhleben.

The remaining tunnels could be converted into an operating section, making it the second exchange line between small and large profile after the Waisentunnel at Alexanderplatz station.

At Bismarckstraße, a new underground railway station had to be built, since the pre-existing tunnel of Line 1 (later renamed U2) was in a bad condition and necessitated extensive repair works.

The costs of the extension to the Spandau city centre rose to unexpected heights: it consumed 680 million German marks as a result of the need to undercut the Havel river and the swampy ground in the surrounding area.

One plan was to lead the subway through the Haselhorster village center, with a downside that the Havel had to be undercut at one of its widest points.

On 1 October 1984, the last section of the U7 from Rohrdamm to Rathaus Spandau was opened, with the then Federal Chancellor of Germany, Helmut Kohl, in attendance.

[citation needed] A southern extension from Rudow to Berlin Brandenburg Airport via Neuhofer Straße, Lieselotte-Berger-Straße, and Schönefeld has already been shelved as the expected patronage was not high enough to justify such an expansion.