The design on which the final building is based was awarded first prize in an invited competition held in 1951. Althought the promulgator of the competition was Hakasalmen Ltd, the building was given the popular name ’Rautatalo’ (the Iron Building), because from the very beginning the intention was that the building should be used to house Finland’s central organisations of ironmongers and builders’ merchants.
The internal day-lighting of the building, which consists almost entirely of offices, is resolved by having a covered light-well in the centre, known as the ’Marmoripiha’ (Marble Court), where the highest gallery is drawn inwards so as not to impede the roof-lighting. The Marmorihalli has acquired the name because the finishing material used there is mainly marble. As well as being an internal source of daylight, the Marmorihalli is the heart of the building from the point of view of both architecture and practicality. It also makes it possible to have shops and a cafe inside the building on the second floor.