The tower is built on the acropolis of the Punico-Roman town of Bithia. Above all, he guarded the area towards S, towards the beach of Chia, ideal for supplying water, and kept under control a territory that was very exposed to pirates landing thanks to the presence of numerous beaches. From the tower, however, it is not possible to see the other coastal towers, so the administration had set up two places to watch and transmit messages at the points called Guardia Grande in N/E and Las Cannas on Capo Spartivento in S/O. The tower was built at
the behest of Viceroy De Moncada in 1578, with the task of defending the mouth of the Rio di Chia, which represented a source of water supply for pirates, contrary to the assessment of Captain Camos (1572). In 1592, the tower was called “I Santi de Quaranta de Quia”, perhaps due to the presence of an early medieval church dedicated to the forty martyrs of Sebaste. Before the construction of the bastion (1572), the area was also called “the master guard”.
The tower was already operational in 1594. It was a 'Torre de Armas', always equipped with 6 and 8-pound guns and a garrison of 5 people, plus another two for each of the two 'dead guard' (i.e. the mobile lookout posts, without a tower).
It has a height of about 13 m and a diameter of more than 10 m. According to a tried and tested pattern spread throughout the S/O sector, it has a very pronounced base plinth and inside the first floor the vault is supported by a massive central column. The structure could not contain more than 5 men; in fact, the men from the lookouts of Las Cannas and Capo Spartivento, who sheltered in the tower at night, were forced to sleep on the terrace under the crescent (a canopy of reeds and tiles above the outdoor terrace, so called for its semicircle shape).
The entrance opened about 5 m above the ground in a N direction. The wall thickness is about 2.5 m wide, inside which there is a staircase leading to the terrace, built in stone steps and originally covered with juniper boards. The external walls are characterized, like the towers of San Macario and Coltellazzo, by well-square limestone ashlars, coming from the ancient city of Bithia, and by rounded pebbles.
In 1605, there was news of the first restorations. In 1614, the tower - being “warden”, (commander of the tower) Leonardo Lucio Obino - had probably been burned by barbarians who stormed the stands. In the parade ground, you can see the traces of three gunboats and two wooden boxes, which protected the hatches and of which there has been news since 1767.
In the Savoy era, the garrison fell to three torrieri plus the gunner and the warden. In 1720, the fortress was in good condition. During these years, the tower maintained its importance and its presence favored the birth, in the 18th century, of the town of Domus de Maria. In September 1769, the engineer Perin and the meter Girolamo Massey prepared a restoration work for the towers of Chia and Coltellazzo, but in 1773 they needed other work according to the report of the Viana meter. An intervention was carried out in 1784, but already in 1786 the warden complained that the new Santa Barbara was already ruined. Other works were carried out periodically since 1806; later in 1818 by the architect Girolamo Melis and in 1840 by the master Rafaele Fadda. After the decommissioning, following the end of the Administration of the Towers, until the 1950s, the Torre di Chia was used by the Guardia di Finanza, to combat smuggling. In 1988 and at the beginning of the 90s it underwent a very heavy restoration.

Bibliography
E. Pillosu, The coastal towers in Sardinia, Cagliari, La Cartotecnica Typography, 1957;
E. Pillosu, “An unprecedented sixteenth-century report on the coastal defense of Marco Antonio Camos”, in New Sardinian Bibliographic Bulletin and Archive of Popular Traditions, V, 1959;
F. Fois, Spanish Towers and Piedmontese Forts in Sardinia, Cagliari, The Sardinian Voice, 1981; G. Montaldo, The coastal towers in Sardinia, Sassari, Carlo Delfino, Sassari 1992; G. Montaldo, Forti And Coastal Towers”, in The fortified architecture of central-southern Sardinia. Proceedings of the Study Day, Cagliari, October 16, 1999;
M. Rassu, Guide to coastal towers and forts, Cagliari, Artigianarte, Cagliari 2000.

How to get to
Chia can be reached from Cagliari following the SS 195 up to km 44.5 where you turn off to Capo Spartivento-Capo Malfatano. To get to the tower, leave Chia and reach the fork where the short trunk (0.7 km) that leads to the beach branches off. From here, on foot, you climb the promontory through a path of about 20 m.