Rio de Janeiro Portuguese pronunciation January River), or simply Rio, is the capital city of the State of Rio de Janeiro, the second largest city of Brazil, and the third largest metropolitan area and agglomeration in South America. There are approximately 6.3 million people living within the city proper, making it the 6th largest in the Americas and 26th in the world. Part of the city has been designated as a World Heritage Site, named "Rio de Janeiro: Carioca Landscapes between the Mountain and the Sea", identified by UNESCO on 1 July 2012 in the category Cultural Landscape. Sources