Gamboa is a part of Rio de Janeiro accessible in Gangstar Rio: City of Saints. It is a low income district, which means that the people living there aren't very rich. Its Boarders Are Urca To South, Flamengo On East, Favela Candído On Southeast.
The apartment of Larissa Santos, in which Angel lives as An Safehouse, as well after the explosion of his car In Mission "One Last Job", is located in Gamboa (it's a typical Gamboa apartment as it's old and not very luxurious), next to the railway tracks.
Other things located in Gamboa are the already mentioned railway tracks, the train station, the container storage yard, the soccer stadium, the old Brasoline refinery (Which Was Destroyed In The Mission "Lube Strike") and the Syndicate headquarters (The Mission "Heroin Heroine" Takes Place Here, Where Been Raided By Police). That's why Gamboa is the territory of The Syndicate and their main operation area.