Rio de Janeiro is a city.
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 . Founded in 1565 by the Portuguese , the city was initially the seat of the Captaincy of Rio de Janeiro , a domain of the Portuguese Empire . This is one of the few instances in history that the capital of a colonising country officially shifted to a city in one of its colonies . Rio de Janeiro was the host of the 2016 Summer Olympics and the 2016 Summer Paralympics , making the city the first South American and Portuguese-speaking city to host the events , and the third time the Olympics were held in a Southern Hemisphere city .