Pritzker Prize laureates Kazuyo Sejima and Ryue Nishizawa of SANAA were revealed today as the winners of an international competition to design the AUD$450 million expansion of the Art Gallery of New South Wales in Australia. As part of the Sydney Modern Project, the expansion will upgrade the existing building into a global cultural landmark that connects the Gallery, the Royal Botanic Gardens and the Domain, the city, and Sydney Harbor.

SANAA scored the commission out of 12 notable shortlisters like Kengo Kuma, David Chipperfield, Herzog & de Meuron, Tod Williams and Billie Tsien Architects, and Renzo Piano Building Workshop, to name a few.

SANAA incorporated the gallery site's surrounding topography and climate in their design, which features cascading platforms of sandstone and glass. The expansion will double the size of the 23,000 sq.m. gallery and will include new educational facilities, spaces for live performances and films, open exhibition spaces, and reintroduce natural daylight into the original 19th-century galleries.

SANAA and the Art Gallery will collaborate in finalizing the design. The expansion already received a $10 million pledge from the NSW government, but the Gallery will need to raise the remaining funds to carry out the project. If all goes smoothly, the new gallery is scheduled for completion in 2021 in time for its 150th anniversary.

Related: Sydney's NSW Gallery announces jurors for museum expansion competition