The Montevideo Cabildo was the seat of government during the colonial times of the Viceroyalty of the Río de la Plata. It is located in front of Constitution Square, in Ciudad Vieja. Built between 1804 and 1869 in Neoclassical style, with a series of Doric and Ionic columns, it became a National Heritage Site in 1975. In 1958, the Municipal Historic Museum and Archive was inaugurated here. It features three permanent city museum exhibitions, as well as temporary art exhibitions, cultural events, seminars, symposiums and forums.