It now seemed natural to continue the line via Dresdener Straße and the Oranienplatz to Neanderstraße (now Heinrich-Heine-Straße) - perhaps too natural: the stretch to Kottbusser Tor would have been very short.
In addition, noting the Karstadt store at Hermannplatz, the Wertheim department store had realised the advantages of a connection to the U-Bahn and reputedly paid 5 million Reichsmarks for a change in the plans.
The line was to begin as elevated track on Schwedenstraße and then continue to Humboldthain via Badstraße.
In 1902, a Nuremberg company, the Continentale Gesellschaft für elektrische Unternehmungen, approached Berlin's executive council, the Magistrat, about building a monorail like the one that had already been built in Elberfeld-Barmen (now part of Wuppertal).
Their preferred route ran from Gesundbrunnen to Rixdorf (later renamed Neukölln).
The GN-Bahn would now be diverted to Moritzplatz and then round a sharp curve to Neanderstraße.
So Wertheim in Moritzplatz also acquired an entrance from the U-Bahn.
The U8 line has had dark blue as its distinguishing colour since it first opened in 1927.
It initially ran between Gesundbrunnen and Neukölln and was therefore known as the GN-Bahn.
The city then received all the tunnel sections which had been built and planned to complete the line itself, but was at the time still in the process of constructing the first north-south U-Bahn.
At that time plans were considered for eventually extending the line, some of them adventurous, for example a connection to the Heidekrautbahn railway to the north and another to the Neukölln-Mittenwald Railway to the south, so that theoretically a mass transit line would have been created extending from Groß Schönebeck in Schorfheide through Berlin to Mittenwalde. The change of oversight had advantages for Berlin, because it made it possible to correct some sections of the route, for example, the northern elevated section, which was entirely eliminated, and the location of the tunnel at the Alexanderplatz.
The segment between Schönleinstraße and Neanderstraße was opened on 12 February 1928 as far as Kottbusser Tor and on 6 April of the same year to Neanderstraße.
A year later, an additional station opened south of Boddinstraße, Leinestraße (in August 1929).
AEG intended to build the line for the wider of the two train formats, known as Großprofil (large profile), like the first north-south line. Like Siemens, AEG had formed a subsidiary elevated railway company, AEG-Schnellbahn-AG.