The church is isolated on a volcanic hill far from the town of Ozieri, from which the surrounding countryside dominates. The place was the seat of the diocese of Bisarchium/Guisarchum documented from 1065-82 and suppressed in 1503. Sant'Antioco di Bisarcio is one of the largest Romanesque churches in Sardinia. The isolation and the scenic position determine a unique combination of landscape and architecture, which qualifies the site as one of the most fascinating in the entire Sardinian architectural landscape.
The church (33 x 12 m, height about 10 m) is made of volcanic stone from local quarries. The impressive dimensional development derives from the function of cathedral of the diocese of Bisarcio. The plant dates back to a period before 1090, the year in which an archival document replicates an older act of possession, which was lost in the fire that destroyed the first cathedral. In the current building, there are three factory periods: the rows of freshly drafted cantons go back to the eleventh century, at the base of the walls of the flanks facing E. The second building phase, after the mid-12th century, is characterized by well-shaped medium-sized cantons. The porch was added at the beginning of the 13th century. The left side of the porch, which collapsed, was rebuilt in the 16th century.
The floor plan has a trench with an E-shaped apse. The central aisle has a wooden roof; the lateral ones have a cross shape. The arches of the seven dividers rise on columns with phytomorphic bases and capitals. In the presbytery there are two pillars with a cross-section, one of which holds a capital with an anthropomorphic figuration.
The apse reflects the Pisan ways of the workers active on the island's construction sites in the middle of the 12th century: divided into mirrors by means of semicolumns with vegetable capital, arcatelles inside which are inserted large rhinestones with bichromic steps.
The thirteenth-century porch has six cross-vaulted bays on cruciform pillars. The upper floor of the porch has three barrel-vaulted rooms, one of which overlooks the central aisle. Within these rooms, used as a bishop's chapel and connected to the episcope, there is a path in the shape of a mitre. On the outside, three arches open in the first order; in the second, a series of ovised arches are arranged. In the large side wall, the ashlar cushions on the walls of the episcope, which developed along the right side of the church, are evident.

History of studies
The building is mentioned by Vittorio Angius (1834) and described by Giovanni Spano (1860). Dionigi Scano considers it in his study on medieval Sardinian churches (1907). The modern reading proceeds through the contribution of Raffaello Delogu (1953), passes through that of Renata Serra (1989) and reaches the profile of Roberto Coroneo (1993). Fernanda Poli is responsible for an in-depth study of sculptural decoration (1999).

Bibliography
V. Angius, entry “Bisarcio”, in Goffredo Casalis, Historical, Statistical and Commercial Geographical Dictionary of the States by H.M. the King of Sardinia, II, Turin, G. Maspero, 1834, pp. 336-337;
G. Spano, “Church and cathedral of the ancient Bisarchic”, in Sardinian Archaeological Bulletin, VI, 1860, pp. 81-91;
D. Scano, History of Art in Sardinia from the 11th to the 14th Century, Cagliari-Sassari, Montorsi, 1907, pp. 200-211; R. De211; R. Scano, History of Art in Sardinia from the 11th to the 14th Century, Cagliari-Sassari, Montorsi, 1907, pp. 200-211; R. De211; R. Scano, History of Art in Sardinia from the 11th to the 14th Century, Cagliari-Sassari, Montorsi, 1907, pp. 200-211; R. De211; R. Scano, History of Art in Sardinia from the 11th to the 14th Century, Cagliari-Sassari, Montorsi, 1907, pp. 200-211; R. De211; R. Scano, History Logu, The architecture of the Middle Ages in Sardinia, Rome, The State Library, 1953, pp. 76, 121-125;
F. Amadu, The Medieval Diocese of Bisarcio, Cagliari, Fossataro, 1963, pp. 11-40;
R. Serra, Sardinia, series “Romanesque Italy”, Milan, Jaca Book, 1989, pp. 262-270; R. Coroneo, Romanesque Architecture from the mid-1000 to the early '300. Nuoro, Ilisso, 1993, sheet 19;
F. Poli, “The sculptural decoration of Sant'Antioco di Bisarcio. New data for old attributions”, in Sacer, n. 6, 1999, pp. 167-199;
G. Piras, “The medieval funerary inscriptions of the Basilica of San Gavino: preliminary contributions for a reinterpretation”, in The Kingdom of Torres 2. Acts of Space and Sound 1995-1997, Sassari, 2003, pp. 302-342; R. Coroneo-R. Serra, Pre-Romanesque and Romanesque Sardinia, series “Italian Artistic Heritage”, Milan, Jaca Book, 2004, pp. 157-166; R. Coroneo, Romanesque Churches of Sardinia. Cultural tourist itineraries, Cagliari, AV, 2005, pp. 51-52.