The Berlin tramway (German: Straßenbahn Berlin) is the main tram system in Berlin, Germany. It is one of the oldest tram networks in the world having its origins in 1865 and is operated by Berliner Verkehrsbetriebe (BVG), which was founded in 1929. It is notable for being the third-largest tram system in the world, after Melbourne and St. Petersburg. Berlin's tram system is made up of 22 lines that operate across a standard gauge network, with almost 800 stops and measuring almost 190 kilometres (120 mi) in route length and 430 kilometres (270 mi) in line length. Nine of the lines, called Metrotram, operate 24 hours a day and are identified with the letter "M" before their number; the other thirteen lines are regular city tram lines and are identified by just a line number.