Lording it over Oristano’s skyline, the Duomo's onion-domed bell tower is one of the few remaining elements of the original 14th-century cathedral, itself a reworking of an earlier church damaged by fire in the late 12th century. The free-standing campanile (bell tower), topped by its conspicuous majolica-tiled dome, adds an exotic Byzantine feel to what is otherwise a typical 18th-century baroque complex.

　　Inside, the look is largely baroque, though a few features survive from the Gothic original, including the Cappella del Remedio, a 14th-century transept chapel, and the Annunziata, a polychrome wooden sculpture of the Virgin Mary in the Cappella dell'Annunziata, variously attributed to 14th-century Tuscan sculptor Nino Pisano or his 15th-century counterpart Francesco di Valdambrino.