São Marcelo Fort started as a triangular bastion, built in wood in the beginning of the 17th century, on a reef in the entrance of the port of Salvador. The Fort has undergone several changes, extensions and adaptions throughout its military history.
It was built to protect the important port city Salvador from threats of the Dutch. The city had the largest number of forts during the colonial period of Brazil. In the end of the 18th century it served as a prison for undisciplined students and important historical characters.