The Spanish tower of Portoscuso, an importantexample of coast tower, rises on a rocky buttress 30m a.s.l. It is part of acoastal defence system set by the Spanish during the second half of the 16thcentury against barbaric raids. It was built of local lava and volcanic tufa in1577 or 1639; the structure, in the shape of atruncated cone, has one floor. Impressive is the dome vault for the presence ofstiffening ribs without central pilaster; outside, the tower is characterisedby decorative corbels. From the terrace you enjoy a charming view of the cityand the Sulcis archipelago.