The Oslo Opera House is the home of the Norwegian National Opera and Ballet, and the national opera theatre in Norway. The building is situated in the Bjørvika neighbourhood of central Oslo, at the head of the Oslofjord. It is operated by Statsbygg, the government agency which manages property for the Norwegian government. The structure contains 1,100 rooms in a total area of 49,000 m2 . The main auditorium seats 1,364 and two other performance spaces can seat 200 and 400. The main stage is 16 m wide and 40 m deep. The angled exterior surfaces of the building are covered with marble from Carrara, Italy and white granite and make it appear to rise from the water. It is the largest cultural building constructed in Norway since Nidarosdomen was completed circa 1300.

More details: https://en.wikipedia.org/wiki/Oslo_Opera_House