Rio used to be the capital up until April 21, 1960, when Braslia was founded by then-Brazilian President Juscelino Kubitschek . It even is considered a World Heritage Site by UNESCO (Buenos Aires is not in Brazil at all, but in neighboring Argentina).

Buenos Aires is the capital and most populous city of Argentina. The city is located on the western shore of the estuary of the Ro de la Plata, on the South American continent's southeastern coast.