The Riksdag is the supreme decision-making body and national legislature of Sweden. As a unicameral parliament comprising 349 members, its primary mandate is to pass laws, determine the central government budget, and examine the work of the government. Its institutional origins trace back to the 1435 assembly in Arboga, eventually transitioning from a four-estate assembly and an 1866 bicameral legislature into its modern unicameral structure in 1971.