Rio de Janeiro, commonly referred to simply as 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, boasting approximately 6.3 million people within the city proper,[4][5] making it the 6th largest in the Americas, and 26th in the world.[6] 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
Source