Germany, Berlin, Potzdamer Platz, Bahn Tower fronted by a replica of the square's clock.

Germany, Berlin, Potzdamer Platz, Bahn Tower.

Germany, Berlin, Potzdamer Platz with Berlin City sightseeing tour bus in the foreground and Bahn Tower in the background.

Germany, Berlin, Potzdamer Platz, Sony Centre with a section of its glass canopied roof and the nearby Bahn Tower.

Germany, Berlin, Potzdamer Platz station with Bahn Tower behind.

Austria, Vienna, Neubau District, The Vienna U Bahn sign for the Untergrundbahn or underground railway. White letter U on circular blue background.

Germany, Berlin, S Bahn sign at Oranienburger Strasse, the S stands for Schnellbahn fast train.

Germany, Berlin, Alexanderplatz, U Bahn sign for Alexanderplatz with Fernsehturm & office building in background.

Germany, Berlin, Alexanderplatz, U Bahn sign for Alexanderplatz with Fernsehturm & office building in background.

Germany, Berlin, U Bahn sign for Alexanderplatz with Fernsehturm reflected in the glass.

Germany, Berlin, U Bahn sign for Alexanderplatz with Fernsehturm reflected in the glass.

Germany, Berlin, Nollendorfplatz is an Berlin U Bahn station located on the U1, the U2, the U3, and the U4. It opened in 1902 and today is the only station in Berlin that is served by four metro lines...