Porto Torres overlooks the sea and its hinterland is crossed by numerous waterways. The modern city was built on the remains of the ancient Roman colony of Turris Libisonis, founded in the 1st century BC. The remains of a bridge and a thermal complex known as the Palace of King Barbarian, named after the one who, according to the hagiographic tradition, sent Saint Gavino, a Sardinian martyr at the time of Diocletian (304 AD), to the torture. The Romanesque Basilica of San Gavino, built in the area of Mount Agellu, a cemetery area inserted in a larger necropolis, is spread between two courtyards, called “Comita atrium” and “Metropolis atrium”.
The Romanesque Basilica of San Gavino di Porto Torres is one of the most significant monuments of the entire Sardinian artistic heritage. The grandeur of the exterior gives way to the discreet charm of the interior, barely illuminated by the light that comes from the single-lancet windows and is reflected in the marble columns and capitals taken from ancient Roman and Byzantine buildings. The sanctuary is also an important devotional destination, due to the millenary cult given to the local martyrs Gavino, Proto and Januarius. At the beginning of the 17th century, the relics of the three saints were searched and discovered there, then placed in the crypt specially excavated to house them.
Various archaeological excavation campaigns have identified the remains of the walls of two older churches, dating back to the V-7th century. One, smaller, is under the N side of the Romanesque basilica, the other extends into the external sector N. Both had three naves but the smaller one had an O-shaped apse, the other in E.
Porto Torres was an episcopal seat from 484 until 1441, the year in which the Turritan bishop moved to Sassari. The first attestation of the church of San Gavino is in the “Condaghe di San Pietro di Silki” and dates back to about 1082. Information about the Romanesque basilica is derived from the “Condaghe di San Gavino”, a founding legend written in the thirteenth century, in which it refers to the votive plant by Gonnario-Comita, ruler of Torres, and the completion by his son, Torchitorio-Barisone I de Lacon-Gunale, judge of Torres in 1065. However, it is not easy to determine the exact chronology of the building, just as the main peculiarity of the church raises numerous questions, ending with two opposing apses (in N/E and S/O), one on each short side, so that the façade is missing and the entrances open along the long sides.
The Basilica of San Gavino is the largest Romanesque monument in Sardinia (58 x 19 m, height 17 m approximately). It has a longitudinal plan with three naves, divided by arches on 22 bare columns and three pairs of cruciform pillars. The factory started from the apse in N/E and ended with the one in S/O. The building was made of Nurra limestone, with the exception of the capitals on which the arches are placed, all marble and reused, from the Roman imperial era except for three Byzantines and one from the 8th century. The central nave has a wooden roof, while the side aisles are vaulted like a cross. Throughout the building, there are single lancet windows that allow light to enter the basilica: some are older, with a stepped frame, then replaced by lights with a smooth strobe.
Outside, the basilica is punctuated in mirrors by a series of pilasters on which arches rest. To the north is the only surviving Romanesque portal, decorated with two human figures depicting Adam and Eve. To the south there is a 15th century portal, in Gothic-Catalan style.

History of studies
The history of studies on the church of San Gavino is very vast, starting with the entry “Portotorre” (1847) by Vittorio Angius, followed by the article by Giovanni Spano (1856) on the ancient city of Torres. From the following century are the contributions of Dionigi Scano (1907), Vico Mossa (1948, 1957, 1988), Raffaello Delogu (1953), focused on historical and artistic issues. The archaeological study by Guglielmo Maetzke dates back to 1989, while the most recent is the monograph by Fernanda Poli (1997), which analyzes all aspects of the monument.

Bibliography V. Angius, "Portotorre", in G. Casalis, Dizionario geografico storico-statistico-commerciale degli Stati di S. M. il Re di Sardegna, XV, Torino, G. Maspero, 1847, XV, pp. 650-654;
G. Spano, "Nome, sito e descrizione dell'antica città di Torres", in Bullettino Archeologico Sardo, II, 1856, pp. 138-147;
D. Scano, Storia dell'Arte in Sardegna dal XI al XIV secolo, Cagliari-Sassari, Montorsi, 1907, pp. 91-110;
V. Mossa, "Recenti restauri nella basilica di San Gavino di Porto Torres", in Studi Sardi, VIII, 1948, pp. 328-353;
R. Delogu, L'architettura del Medioevo in Sardegna, Roma, La Libreria dello Stato, 1953, pp. 16-18, 85-92;
V. Mossa, "Rilievi e pensieri sul patrimonio monumentale di Porto Torres", in Studi Sardi, XIV-XV, 1955-57, pp. 371-388;
P. Sanpaolesi, Il Duomo di Pisa e l'architettura romanica toscana delle origini, Pisa, Nistri-Lischi, 1975, pp. 43-49;
V. Mossa, S. Gavino di Torres, Impianto-Inserti-Restauri, Sassari, Chiarella, 1988;
G. Maetzke, Monte Agellu, Le origini della basilica di San Gavino di Porto Torres secondo le testimonianze archeologiche, Sassari, Chiarella, 1989;
R. Serra, La Sardegna, collana "Italia romanica", Milano, Jaca Book, 1989, pp. 183-212.
R. Coroneo, Architettura romanica dalla metà del Mille al primo '300. Nuoro, Ilisso, 1993, scheda 1;
A. Mastino - C. Vismara, Turris Libisonis. Sassari, C. Delfino, 1994 (Sardegna archeologica. Guide e itinerari; 23);
G. Dore, San Gavino di Porto Torres. Il portale romanico, Sassari, Poddighe, 1997;
F. Poli, La basilica di San Gavino a Porto Torres. La storia e le vicende architettoniche, Sassari, Chiarella, 1997;
G. Piras, "Le iscrizioni funerarie medievali della basilica di San Gavino: contributi preliminari per una rilettura", in Il Regno di Torres 2. Atti di Spazio e Suono 1995-1997, Sassari, 2003, pp. 302-342;
R. Coroneo-R. Serra, Sardegna preromanica e romanica, collana "Patrimonio artistico italiano", Milano, Jaca Book, 2004, pp. 76-91;
R. Coroneo, Chiese romaniche della Sardegna. Itinerari turistico-culturali, Cagliari, AV, 2005, pp. 23-25;
Il Condaghe di San Gavino, a cura di G. Meloni, Cagliari, CUEC, 2005.