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, 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.
The city was the capital of Brazil for nearly two centuries, from 1763 to 1815 during the Portuguese colonial era, 1815 to 1821 as the capital of the United Kingdom of Portugal, Brazil and Algarves, and 1822 to 1960 of Brazil as an independent nation. Rio is nicknamed the Cidade Maravilhosa or "Marvelous City".
Rio de Janeiro represents the second largest GDP in the country (and 30th largest in the world in 2008),estimated at about R$343 billion (IBGE/2008) (nearly US$201 billion), and is headquarters to two of Brazil's major companies—Petrobras and Vale, and major oil companies and telephony in Brazil, besides the largest conglomerate of media and communications companies in Latin America, the Globo Organizations. The home of many universities and institutes, it is the second largest center of research and development in Brazil, accounting for 17% of national scientific production—according to 2005 data.