Ilha Grande (Portuguese pronunciation: [ˈiʎɐ ˈɡɾɐ̃dʒi] "Big Island") is an island located off the coast of Rio de Janeiro state, Brazil. The island, which is part of the municipality of Angra dos Reis, remains largely undeveloped. For almost a century it was closed by the Brazilian government to free movement or settlement because it first housed a leper colony and then a top-security prison. Cândido Mendes high-security prison housed some of the most dangerous prisoners within the Brazilian penal system.