Sant'Antioco di Bisarcio is one of the largest Romanesque churches on the island. Its scenic location makes it one of the most beautiful structures in the entire Sardinian architectural landscape. Built with blocks of volcanic stone from local quarries, it became the cathedral seat of the Bisarcio diocese until 1503.
On the inside, the building shows three periods of construction: an early 11th-century layout is characterised by barely sketched cantons at the base of the masonry on the east side, the second building phase, after the mid-12th century, is characterised by well-shaped, medium-sized cantons, the portico was added at the beginning of the 13th century. The floor plan is three-aisled with an apse to the east. The nave has a wooden roof, while the side aisles are vaulted.