The museum building is designed by Irma and Matti Aaltonen. Wäinö Aaltonen himself took part in the designing process. Aaltonen travelled a lot, and he had got acquainted with different museums during his travels and exhibitions abroad. After the decision was made by the city to build the museum, Aaltonen was granted a travel scholarship that enabled him to travel and study the trends of museum architecture in Europe.
The influence of the artist can be seen in the spacious exhibition rooms that enable the visitors to view three-dimensional art from every angle. When the musealic whole was being planned, specific spaces were reserved for specific forms of art. The upper and lower galleries were planned for miniature sculptures, paintings and graphics. The sculpture hall, 11 metres in height, was planned for large works of art. The sculpture hall has since given unique settings to numerous works of contemporary art, the displaying of which would have been impossible elsewhere.
The atmospheric atrium illuminates all the space that surrounds it. Through the large windows, the visitors are able to see the sky or the rippling water of the pool. Susanna, a bronze sculpture by Aaltonen, is kneeling by the pool.
The museum building contains elements from the World's Fair Pavilion (1929, reconstruction in 1986) in Barcelona, Neue Nationalgalerie (1968) in Berlin, both by Mies van der Rohe, and from the Munch Museum in Oslo by Einar Myklebust ja Gunnar Fougner. The travertine facade, water theme in the atrium and the floor design all have an international feel to them. However, the architecture of the museum is very down-to-earth, and there are not many traces of luxury. Economy and flexible space utilisation were the main goals of the planning process. Expensive and complex solutions were avoided in the realisation. The result is a functional museum building that operates solely on terms of fine arts.