The sketches did not take definitive form until 1955, when construction finally got under way. The house was inaugurated in 1958. Aalto tackled the job as three separate assignments, giving the building a tripartite structure. Originally the whole complex was to be faced with red brick, but the plans later changed. Aalto built a rectangular, copper-clad office wing with five storeys above ground and a large, free-form auditorium of red brick connected by a lower wing, forming a small piazza.
The office wing contains 110 offices, meeting and conference rooms, and hobby rooms. The connecting wing contains a lobby and cloakroom, a lecture auditorium, three classrooms, five meeting rooms, a library, and a large gymnasium at basement level. The main rooms of the auditorium wing are a large congress and concert hall with seating for 1,500, a restaurant, and a small basement cinema (today used as a meeting room).
The whole complex is held together by a column-borne copper canopy that runs alongside the street for 60 metres and forms a portico to the little piazza, which features a fountain by Wäinö Aaltonen in the form of an open hand.
According to Aalto the form of the House of Culture auditorium was dictated by acoustic considerations: “The various uses of the room require first-class acoustics, which is the reason for the form, a concrete helix combined with wood and brick. Specially designed wall and ceiling surfaces both absorb and reflect sound waves. Substitute wall panels can be used for various acoustic needs ” for an empty or full house, for concerts or congresses – without disrupting the architectural rhythm. Aalto’s hopes were fulfilled: the House of Culture became known for its excellent acoustics, and is used frequently for concerts as well as orchestra rehearsals and recordings.
The monolithic exterior of the auditorium wing, which closely follows the helical form of the interior and is almost windowless, displays variously bent brick surfaces, which could not have been built without the specially manufactured standard wedge-shaped brick invented by Aalto for the purpose.