In 1923 a competition was held to choose a site for a new parliament house. Arkadianmäki, a hill beside what is now Mannerheimintie, was chosen as the best site.
The architectural competition which was held in 1924 was won by the firm of Borg–Sirén–Åberg with a proposal called Oratoribus (Latin for “for the speakers”). Johan Sigfrid Sirén (1889–1961), who was mainly responsible for preparing the proposal, was given the task of designing Parliament House. The building was constructed 1926–1931 and was officially inaugurated on March 7, 1931.