Norway will open its new $650 million National Museum to the public on Saturday, unveiling a vast permanent exhibition of art through the ages that puts it on a par with some of the world's greatest museums.

Designed by German architect Klaus Schuwerk, the large, boxy building complex on the Oslo waterfront took eight years to complete and brings together the collections of five Norwegian art and design museums under one roof. With 13,000 square meters of exhibition space and 6,500 artworks permanently on display, including Edvard Munch's "The Scream", the museum will be the largest in the Nordic countries and in the same league as the Guggenheim in Bilbao, Spain, or the Rijksmuseum in Amsterdam.

Built with materials intended to last for centuries, the museum's buildings are decked in blue-grey local slate and crowned with a translucent Light Hall which is covered in glass and marble. The hall will be used for temporary exhibitions, and kicks off with "I Call It Art" which features works by artists currently working in Norway on themes of identity, belonging, nationality and democracy.

"It's fantastic to work in a space where you have the possibility to make any kind of exhibitions - hanging stuff from the ceilings, build and use all the elements," said Stina Hoegkvist, the museum's director of exhibitions and collections. The museum's planned shows include exhibitions of works by U.S. abstract painter Mark Rothko and Mexican surrealist painter Frida Kahlo, both in 2024.

Designed to maximise energy efficiency and minimise greenhouse emissions, the museum is heated and cooled by water from the Oslo fjord on its doorstep. "It is monumental and beautiful but also discreet and intimate at the same time," the museum's director, Karin Hindsbo told Reuters. The museum has been the subject of some controversy after the project suffered delays and needed government support when it ran out of cash. It was initially meant to open in 2020.

The design has been criticised for its "blocklike" structure and the of 'schist', a striped grey Norwegian slate, to cover the facade. "There has been a lot of debate, but that is how it's supposed to be," Hindsbo said. ($1 = 9.4725 Norwegian crowns) (Reporting by Victoria Klesty Editing by Raissa Kasolowsky)