The site of Setúbal has been occupied since prehistoric times, successively by Phoenicians, Carthaginians and Romans.
Privileged Atlantic port, the first defensive structure of this important village was a wall started at the time of King D. Afonso IV (1325-57) and completed in the following reign, under D. Pedro I (1356-67), with the function of containing attacks by pirates and corsairs, usually from North Africa.