The Berlin U-Bahn is an electric rapid transit system in Berlin, the capital and largest city of Germany, and a major part of the city's public transport system. Together with the S-Bahn, a network of suburban train lines, and a tram network that operates mostly in the eastern parts of the city, it serves as the main means of transport in the capital.
Opened in 1902, the U-Bahn serves 175 stations spread across nine lines, with a total track length of 155.64 kilometres (96 miles 57 chains), about 80% of which is underground. Trains run every two to five minutes during peak hours, every five minutes for the rest of the day and every ten minutes in the evening. Over the course of a year, U-Bahn trains travel 132 million kilometres (82 million miles), and carry over 500 million passengers.