Escolhi um sítio que parecia mais conveniente para edificar nele a cidade de São Sebastião o qual sítio era de um grande mato espesso cheio de muitas árvores grossas em que se levou assaz de trabalho em as cortar e a limpar o dito sítio e edificar uma cidade grande cercada de muro por cima com muitos baluartes e fortes cheios de artilharia, e fiz a igreja dos padres de Jesus onde agora residem telhada e bem consertada
Panorama do morro do Castelo visto da igreja da Glória, Richard Bate. 1809. (Biblioteca da Universidade de Cornell, EUA)
In 1567, Morro do Castelo became the nucleus of the city of São Sebastião do Rio de Janeiro, founded two years earlier. In its early years of occupation, the hill was fortified to shelter the Portuguese settlers and resist any retaliation attempt by the French – allied with the Tupinambás – who had been defeated and expelled from the city.
The Castelo then occupied an area of 184 thousand square meters. Its height reached 63 meters, and the hill was bounded on its four sides by what are now Rio Branco Avenue (formerly Avenida Central) and Santa Luzia, Misericórdia, and São José streets. It was surrounded by walls and bastions full of artillery, following the Portuguese model of "acropolis-cities" – that is, built on higher, fortified ground in order to favor watch-keeping and the defense of the urban core. Within the walls stood the Casa da Câmara, the jail, the royal warehouses, and the church of Santo Inácio dos Jesuítas, alongside the Colégio da Companhia de Jesus and the three-nave Sé.
Morro do Castelo tomado do morro de Santa Tereza, Friedrich Salathé. 1835. (Divisão de Iconografia/Fundação Biblioteca Nacional)
At the foot of the hill, on Pontal de Santiago (later Ponta do Calabouço), the Forte de São Tiago was built, and at the top the Forte de São Sebastião was built, which, seen from below, looked like a medieval castle. Hence the name Morro do Castelo.
Panorama da cidade (detalhe), Luís dos Santos Vilhena, 1775. No topo do Morro do Castelo, à direita, o forte de São Sebastião (7). À esquerda, a Igreja de Santo Inácio e Colégio dos Jesuítas (6). Fundação Biblioteca Nacional