The Palácio Monroe was a monumental hall in the Centro neighbourhood in Rio de Janeiro, Brazil. It was originally built in St. Louis to act as the Brazilian Pavilion during the 1904 World's Fair. Following the World's Fair, the building was dismantled and transported in cargo ships to Rio de Janeiro, where it was rebuilt in 1906. Its grand opening at the 3rd Pan-American Conference was held on July 23, 1906. From 1914 to 1920, the palace was used as the home of the Brazilian Congress. From 1925 to 1960 it was used as home to the Brazilian Senate. On October 11, 1975, the Brazilian president Ernesto Geisel authorised the building's demolition. The decision was contrary to the Rio de Janeiro State's decision declaring the building an Official Landmark in 1974.