Copenhagen Metro is a 24/7 rapid transit system serving the cities of Copenhagen, Frederiksberg, and Tårnby in the Capital Region, Denmark. The 20.4-kilometre (12.7 mi) system opened between 2002 and 2007, and has two lines, M1 and M2. The driverless light metro supplements the larger S-train rapid transit system, and is integrated with DSB local trains and Movia buses. Through the city center and west to Vanløse, M1 and M2 share a common line. To the southeast, the system serves Amager, with the 13.9-kilometre (8.6 mi) M1 running through the new neighborhood of Ørestad, and the 14.2-kilometre (8.8 mi) M2 serving the eastern neighborhoods and Copenhagen Airport. The metro has 22 stations, of which nine are underground. In 2013, the metro carried 55 million passengers.