The contract is worth about SEK700m (£62.6m) and includes renovation of the main building, installation of lifts and construction of a culvert connecting the buildings.
Nationalmuseum has a gross area of 21,000m2 for the main building and 1,200m2for the annex.
ɫèֱ²¥ start is planned for August 2014, and the renovation works will be completed in June 2017.