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The Norwegian National Opera and Ballet was designed to be a democratic structure, where visitors—whether they hold a ticket or not—can explore the Carrara marble–clad roof plaza and lobby. Completed in 2008, the building has become the jewel of the Oslo waterfront district and spurred more development, helping to revive the area.

See How Snøhetta’s Architecture Brought the Best of Scandinavian Design to the World

A new book surveys the AD100 firm, which has designed such high-profile structures as the National September 11 Memorial Museum Pavilion to lesser-known buildings like the Norwegian Wild Reindeer Pavilion