Netherlands-based The Office for Metropolitan Architecture (OMA) has won a competition for a major expansion to the Musee national des beaux-arts du Quebec (MNBAQ) in Quebec, Canada.

The 12,000sq m new building, effectively three overlapping boxes, will be situated at the point where downtown Quebec City meets Battlefields Park and form the company's first built project in Canada. The design, led by OMA partners Shohei Sigematsu and Rem Koolhaas in collaboration with associate Jason Long, was chosen unanimously from five submissions. The expansion - linked underground with MNBAQ's three existing buildings - is located on Quebec's main promenade, Grande-Allée, adjacent to St. Dominique Church. The design aims to integrate the building with the surrounding park and initiate new links with the city.

Three stacked galleries of decreasing size - housing contemporary exhibitions (50m x 50m), the permanent contemporary collection (45m x 35m) and design/Inuit exhibits (42.5m x 25m) - will rise from the park towards the city, forming a cantilever towards the Grande-Allée and a 14m-high Grand Hall. Shigematsu said: "Our ambition is to create a dramatic new presence for the city, while maintaining a respectful, even stealthy approach to the museum's neighbours and the existing museum.

"The resulting form of cascading gallery boxes enhances the museum experience by creating a clarity in circulation and curation while allowing abundant natural light into the galleries." The project will be undertaken by OMA's New York office in collaboration with Provencher + Roy Associes Architectes, with an anticipated completion date of autumn 2013.