Rio de Janeiro is a metropolis.
Greater Rio de Janeiro , officially Rio de Janeiro Metropolitan Region ( Grande Rio , officially Região Metropolitana do Rio de Janeiro , in Portuguese ) is a large metropolitan area located in Rio de Janeiro state in Brazil , the second largest in Brazil and third largest in South America . The metropolitan area of Rio de Janeiro is known as a historical , cultural and economic centre of Brazil , with a total population of 12.6 million inhabitants . Rio de Janeiro ( [ ˈriːoʊ_di_ʒəˈnɛəroʊ , _ - deɪ_ʒə - , _ - də_dʒə - ] [ ˈʁi.u d ( ʒi ) ʒɐˈnejɾu ] ; River of January ) , or simply Rio , is the second-most populous municipality in Brazil and the sixth-most populous in the Americas . The metropolis is anchor to the Rio de Janeiro metropolitan area , the second-most populous metropolitan area in Brazil and sixth-most populous in the Americas .