Rio de Janeiro is a city.
This is a list of the 33 administrative regions ( in região administrativa ) in the city of Rio de Janeiro , Brazil . 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 . Part of the city has been designated as a World Heritage Site , named `` Rio de Janeiro : Carioca Landscapes between the Mountain and the Sea '' , by UNESCO on 1 July 2012 as a Cultural Landscape .