The Forte de São Sebastião also known as Castelo de São Sebastião stands out in the fortification complex of Porto Pim Bay. It was built in the 17th century with volcanic tuff, a material that was more accessible and easier to handle, extracted from Monte da Guia.
The Castle stood out in the island’s defensive system, having played an essential role in monitoring the entrance to Porto Pim Bay and the movement facing the south of the island.
It was one of the few military structures to be recovered, around 1817, having served as a prison, approximately until the end of World War II.