The church of St. Sixtus is first mentioned in 1278, when the five parishes of the walled city were established. By 1848 it was rebuilt in Neoclassical style from the foundations, so that no trace remains of the Gothic layout. It has a simple gabled facade characterized by an upper gable supported by two pilasters on each side. Centrally, the raised portal on a staircase leads into the single-nave interior, covered by a barrel vault and having three chapels on each side. The interior furnishings of the chapels are almost entirely of modern age, with the exception of the high altar coeval with the first installation and the neoclassical altar in the second chapel on the left. Also in the neoclassical style is the pulpit placed in the hall on the right side, near which the 18th-century statue of St. Sixtus is visible. For the church of S. Sisto the Sassarese painter Costantino Spada created around 1950 the frescoes of the apse basin and those above the triumphal arch, depicting the Last Supper, the Apotheosis of the Immaculate Virgin and the Martyrdom of S. Sisto. By the same author are two canvases depicting a Crucifixion and a Baptism of Christ. Of considerable interest is the polychrome wooden Crucifix dating from the 12th century.
