The Calasetta Tower, located in the historic center of Calasetta, dates back to 1756. It was erected to provide protection from attacks from the sea and today is used for cultural and educational activities and to house an important collection of Phoenician-Punic artifacts. Atta to guard the entire stretch of sea and coastline between the islands of Sant’Antioco and San Pietro and the mainland, it allowed a view that spanned a radius of 20 km. Calasetta’s massive tower has a classic truncated cone shape with a base diameter of more than 16 meters and a height of 11 meters at the terrace. It consists of two overlapping rooms, of which the one below – containing the ancient cistern – was unearthed in recent times. The external staircase, also of modern age, leads to the entrance located at a height of 4 meters. One enters a circular chamber 10 meters in diameter, covered with a domed vault supported by a pillar. The chamber is divided into several rooms by some partitions already of planting, of which the alcad and soldiers’ quarters can be recognized. All the thrones and the hatchway of this chamber are arranged symmetrically as at the corners of a regular hexagon. From the open staircase to the right of the hatchway and carved into the wall thickness, one arrives at the slab of arms, now unrecognizable after various interventions that have transformed battlements, gunports and sentry boxes. Part of the stone stringcourse remains of the ancient structure.