Considered one of the last great fortifications built in the colonial period, the fortress is located on Ilha do Mel, controlling access to Baía de Paranaguá. Built of stone on the former Praia da Baleia, now Praia da Fortaleza, it is an imposing fortification with high walls, but without bastions or other attached defensive structures. Its function was to defend the bay against privateers, pirates, and rebels. In the early 20th century, the fortification entered a crisis and was gradually abandoned. In 1938, it was listed by IPHAN and later came under the management of the state government, which carried out reforms, implemented a museum and forest post, and opened it to tourism.