The U7 is a rail line on the Berlin U-Bahn. 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. The line was originally the south-eastern branch of the Nord-Süd-Bahn (U6) that ran between the branching point at Belle-Alliance-Straße (Mehringdamm) and Grenzallee; however, in the 1960s, this stretch was separated from the rest of the line and extended at each end to form a new line. As of 2007, the U7 is Berlin's longest underground line, both in terms of absolute length and total travel time, and one of the longest (entire) subterranean lines in Europe.
