This cathedral, built between 1284 and 1288, has a Romanesque-Gothic façade with all the elements of the Pisan style, including the windowless arcature of the upper level. The bell tower has been substantially remodelled; the oldest of the four bells (1337) is the work of Andrea Pisano. When it was extended in the late 16C the edifice was given elements of Aragonese Gothic style. Be sure to admire the superb vault on the diagonal ribs in the central nave and the altar of Sant'Antioco.