In collaboration with the municipal authorities of Copenhagen and Frederiksberg, the Danish government has concluded a contract to expand the existing metro with a new city circle line, Cityringen.
Cityringen is a completely new metro line constructed on the same principles as the existing Copenhagen metro net. Cityringen will be a 15.5 km underground railway under downtown Copenhagen, the "bridge quarters" and Frederiksberg. The circle line will have 17 underground stations and opens in July 2019.
In the end of 2019 the two stations of the Nordhavn extension will be linked to Cityringen. I 2023 the Sydhavn extension and its five extra metro stations will also be a part of the Copenhagen metro network.