Last friday me and my boyfriend visited the new underground line U55. Officially opened on 8 August 2009, it now has only three stations and is not connected to any other underground train.
Actually, there were plans to extend line U5 from its current western terminus at Alexanderplatz through the city centre, past the Brandenburg Gate and the Bundestag, to the new central train station, Berlin Hauptbahnhof. This Chancellor Line ("Kanzlerlinie"), it's named like that because it passed through the government quarter, was originally planned as a diagonal line through central Berlin, continuing to Turmstraße in Moabit, where it would have a passage to get to the the U9, and on to Jungfernheide, where it would connect with the S-Bahn ring and U7. Beyond the S-Bahn ring, the line might continue to Berlin Tegel Airport or—if the airport is closed as planned—to the new neighbourhoods to be built in its place. Because this was a long-planned route, short tunnels are existing at both Jungfernheide and Turmstraße to incorporate the new line.
However, these plans were cut back for financial reasons before construction even began. For now, the line terminates at the Hauptbahnhof and is planned to be built further at an unspecified later date.
So we used the time, going by the "U-Bahn" the two stations to "Hauptbahnhof" and were impressed by the kind of decadent architecture and the tidiness, which is caused by the lack of people using this line. I really liked the kind of windows to let light incide at the station "Bundestag", it gives you a certain feeling.
If you are around in Berlin and haven't visit the line before, give it a try!
(my outfit pictures were shot by my boyfriend, the other pictures by me and the informations came from wikipdia.co.uk)