Fort São Sebastião
Fort São Sebastião lies in the village of Castro Marim, in the province of Algarve in Portugal. It is locally known as Forte de São Sebastião de Castro Marim.
Castro Marim is a peculiar village; it is situated between two hilltops and on each of the hilltops stands a robust fortification; Castro Marim Castle and Fort São Sebastião. The border with Spain; the Guadiana river, is just 2 kilometers to the east.
Already in 1242 Castro Marim Castle was situated on the northern hilltop.
In 1641 King João IV ordered the construction of Fort São Sebastião on the southern hilltop. At that time Castro Marim Castle was being reconstructed again and the two bulwarks were connected with walls that also enclosed the village between them.
Nowadays both bulwarks lie in ruins and the connecting walls have largely disappeared. This is a nice example of border fortification architecture over the centuries. The castle can be visited for a small entrance fee. The fort is freely accessible.