Eight of the numerous stations that make up today’s U4 and U6 subway lines have been maintained as they were when first built by Otto Wagner: Schönbrunn and Stadtpark (U4) as well as Gumpendorfer Strasse, Burggasse, Josefstädter Strasse, Alser Strasse, Währinger Strasse and Nussdorfer Strasse (U6). Another pair of particularly fine station buildings can be found on Karlsplatz.