COPENHAGEN, Sept. 29 (Xinhua) -- Denmark's Queen Margrethe II on Sunday opened 17 additional metro stations at the City Hall Square in the capital city of Copenhagen.

Known as the City Circle or Cityringen in Danish, the new stations will expand the reach of the Danish city's current driverless metro system to 37 stops.

"The subway is now such an integral part of the city that no one would imagine the city without it," said Queen Margrethe at City Hall Square at the official opening ceremony.

Danish Prime Minister Mette Frederiksen along with Copenhagen's mayor, Frank Jensen, Minister of Transport Benny Engelbrecht and other politicians also attended the opening ceremony.

The platform floors at the 17 newly constructed metro stations, like the 20 others, are built with Chinese granite.

The dignitaries at the opening became the first passengers of the first train departing from City Hall Square's new station.

The entire system is now officially open to the general public. To mark the opening of the new stations, all bus, train and metro travel within Copenhagen has been declared free on Sunday till midnight.