Villasor lies on a fertile plain, irrigated by Flumini Mannu and other streams, which has favoured agriculture since the Roman times to which the necropolises date, as do the remains of a bridge and a settlement near the s'Acqua Cotta spring. Villasor is a town of 7,000 inhabitants in the southern Campidano area, founded in 1414 on the ruins of Sorres (Latin for 'granary'). The county was first ruled by the Spanish Crown (1537), then marquisate (1594). Today, it is one of the main agricultural hubs of southern Sardinia, with outstanding production and processing of sugar beet and grains. The old town retains its legacy of a glorious past: the Castle of Villasor, built in 1415 by the feudatory Giovanni Siviller on the ruins of the Byzantine church of Santa Maria di Gippi, the marbles of which are preserved in the National Archaeological Museum of Cagliari. Built to defend against the assaults of the surviving Arboreal rebels, its architecture is unique for Sardinia, uniting civil and military aspects, also known as the Casa-forte degli Alagon, after one of the oldest European families, to whom the fortress belonged until the abolition of the feud (1839). The structure has an imposing U-shape, with the main façade bearing a round arch portal and windows with Gothic-Catalan frames. Guelph battlements form the crowning. The interior is split across two levels, with a wooden truss ceiling inside and an external roof. Over the centuries, the building has been used as barracks, a prison, a school and agricultural shed. Currently, the rooms host exhibitions and conferences.
Dating back to the same time as the castle is the parish church of San Biagio, built in Gothic-Catalan style based on the model of San Giacomo in Cagliari and restored between the 18th and 19th centuries. The interior recalls the cathedral of Cagliari, with a Latin cross layout, three naves, octagonal dome and a presbytery surrounded by a marble balustrade supported by lions, housing a baroque altar. The altar of the Madonna del Rosario and an 18th-century statue of Sant'Efisio are also of great value. The patron saint is celebrated on 2nd February. The church of Santa Vitalia was built at the end of the 14th century on the site of an ancient building, today being a suburban area. A much-loved festival takes place in mid-October in honour of the martyr. The church of Sant'Antioco safeguards a baptismal font from 1743, an altar with a painting from the 17th-18th centuries, two inlaid wooden altars and a Byzantine marble depicting a lion and a bull. Celebrations for the martyr of Sulcis are held shortly after Easter. The sanctuary is contemporary and linked to the former convent of the Capuchins, founded in 1630, which went on to become a town hall, school, kindergarten, then finally a library. The greatest Nuragic remnants is Su Sonadori, in s'Acqua Cotta (12 kilometres from the town), a complex consisting of a central tower with a diameter of ten metres, dating from the middle and recent Bronze Age, surrounded by a bastion formed by six 'autonomous' buildings, differing in shape and size, connected by curtain walls. All around are the remains of village huts.