The building is designed by the American architect Steven Holl.

The main entrance near the statue of Marshal Mannerheim leads the visitor into a high lobby under a glass ceiling. This lends the building personality, which develops in increasingly clearer forms as one walks towards the auditorium and the galleries. A curving ramp leads from the ground-floor lobby towards the core of the museum in the distance. The design is based on ideas about the golden section, Zen-like peace, a human scale. These principles are manifested, for example, by the spatial sequences on the first and third floors, by the lines and details of the galleries. All services, from security and ventilation to exhibition technology, are concealed within the wall structures.

Fluorescent lamps in the galleries are installed in special 'light pockets', providing indirect, tranquil light for the galleries. In earlier times, lighting in art museums was expected to be uniform and static, but Kiasma has deliberately opted for a different solution. Because natural light changes depending on the direction it comes from, different galleries have different natural lighting conditions. The galleries can also be darkened.

The principle of simplicity is also manifest in the choice of materials. The walls are plastered white, the floors are tinted concrete without skirting boards. The walls of some galleries are curved or positioned obliquely, representing a conscious choice of searching for a challenge to the plurality of contemporary art. The yellow doors of the seminar room on the ground floor and the dark red used in the info desk and cloakroom provide splashes of colour. The ceiling of the café and museum shop is painted reddish brown.

The spaces of Kiasma are designed to embody a roughness that is typical of places where contemporary art best comes into its own. Features which develop naturally in old factories and warehouses have in Kiasma been given a new, deliberate form, expressing an austerity characteristic of working spaces.

Materials

The curved roof of the building is made of solid zinc with a few per mille of titanium and copper. It has been patinated to emulate the effect of about 5 years' weathering. The surface will darken slightly more with time. The vertical windowless elevations are aluminium, which is resistant to Helsinki's maritime climate. They are sandpapered by hand using a horizontal movement, giving the aluminium a surface that refracts light. The aluminium walls are allowed to develop a natural patina. The south and north elevations have reddish surfaces. These are made from acid reddened, textured brass, treated with heat and chemicals. The building's big double-curved glass wall is made from Reglit glass u-blocks, which are mainly used in industrial buildings. The greenish element (ferric dioxide) has been removed from the building's glass walls and gallery windows in order to ensure that the light entering is natural daylight. Most of the glass surfaces are sandblasted, but using aluminium oxide or silicon dioxide instead of sand. This creates a prismatic surface that refracts light beautifully. The other glazed walls of the building are steel curtain walls. The walls and ceilings are white plaster, with the aim of creating tranquillity and simplicity. The floor is dark grey, almost black, concrete. The high double-curved concrete wall of the entrance hall is concrete cast in a horizontal board mould and painted white. The auditorium walls are reddish plywood. A special feature of the auditorium is the control booth, upholstered in fabric that gives the impression of dark blue velvet.

Details

Area. Work on building the museum began in 1996, with a budget of FIM 227 million. The gross floor area is about 12,000 m², of which the exhibition spaces account for 9,200 m².

Light. One of the key elements of Kiasma is light. The building has a great number of transparent surfaces. The big double-curved glass wall is made from glass planks, which are mainly used in industrial buildings. The greenish element has been removed from the building's glass walls and gallery windows in order to ensure that the light entering is natural daylight. The amount of light is controlled electronically to take into account seasonal and daily fluctuations. Because of the curved roof, the 'bow-tie' windows presented a challenge for the builders. The artificial lighting was designed by Hervé Descottes (L’Observatoire International, Paris, New York) together with Steven Holl and Vesa Honkonen. Julle Oksanen provided technical assistance in the details. All special lights in the public areas are based on sketches by Steven Holl. For example, his line is visible in the sandblasted aluminium lights and in the 'flowing ice' on the café ceiling.

Scale. The scaling in Kiasma is based on the dimensions of the human body. One of the basic dimensions employed by Steven Holl is 165 centimetres, the viewing height. The height and width of the doors, the square pattern on the sliding doors and the scaling of spaces are based on the golden section.

Furniture and fittings. All fittings, as well as toilet furniture, are designed by Steven Holl. He also designed many of the details, such as wall hooks and door handles. The tables and green chairs in the cafe are designed by Vesa Honkonen. The three unique Star Trek highchairs are designed by Stefan Lindfors.

Pool. The water motif, which is a central element in the exterior design, begins at the foot of the statue of Marshal Mannerheim, runs along the building in a black granite pass and ends at the northern end of the building. In future, the pool may be extended all the way to Töölönlahti Bay, depending on future construction in the area.

Outdoor lights in front of Kiasma were designed by Juhani Pallasmaa. Pallasmaa also designed the street and yard spaces around the statue of Mannerheim. The lawn area facing the Parliament building was designed by Steven Holl.

Kiasma Stage. The stage, erected in summer for various happenings, was designed by Roy Mänttäri.