blocks from the Copenhagen borough of Nørrebro. The Forum area is a residential area built during the 1930s and 1940, built in functionalism, and hosts the Royal Danish Academy of Music. Nørreport lies within Indre By—the city center of Copenhagen. It is the main intersection with DSB's intercity and regional trains, as well as the S-train, serving lines A, B, C, E and H. Kongens Nytorv lies at the heart of the commercial and cultural center of Copenhagen. When the City Circle Line opened, the station serves as the transfer to lines M3 and M4. Christianshavn is located on an island, a former navy base that has been redeveloped into residential and commercial mix. It is the last station served by both lines, with M1 branching off towards Westamager, and m2 continuing towards Lufthavnen. Amagerbro is located in the borough of Amager Øst, and is the first station on the island of Amager. The surrounding area combines a residential area with night life and many shops. Lergravsparken is surrounded by an older, dense residential area, although it has experienced commercial growth after the metro arrived. After Lergravsparken, the line emerges and runs on an embankment or elevated the rest of the way to the airport. The line also enters the municipality of Tårnby and passes into fare zone 3. Øresund is located in an industrial area, and is one of only four stations to have no bus service. Amager Strand is located from Amager Beach Park, that runs along the coast of Amager. This station also has no connecting bus services. Femøren is located in an industrial area, but also near the park Tiøen. Kastrup is the first station in fare zone 4. It is located in a predominately industrial area, but the area also features a marina and other aquatic leisure facilities. Lufthavnen (the Airport) is the terminus of M2. It is located at Terminal 3 of Copenhagen Airport, the largest airport in the Nordic countries and the main hub for Scandinavian Airlines, and a hub for Norwegian Air Shuttle. There is also transfer to the mainline train station, which serves DSB's intercity and regional trains, and international trains to Sweden, the regional Oresundtrain and SJ's X 2000 intercity service to Stockholm. Service The Copenhagen Metro system operates continually (24/7) with a varying headway throughout the day. During rush hour (07:00–10:00 and 15:00–18:00), there is a four-minute headway on