Announcing the presence of the cathedral is its landmark bell tower topped by a brightly tiled cupola. The cathedral itself, which sits on a panoramic terrace, was originally Gothic but a protracted 17th-century remodelling saw the addition of Renaissance and baroque elements.
Inside, the main altar is dominated by the Madonna in trono col Bambino, a painting by the mysterious Maestro di Castelsardo. More of his works can be seen in the Museo Diocesano in the crypt .
Accessible through a door next to the altar, the crypt features a series of small rooms chiselled out of the living rock. These are all that remain of the Romanesque church that once stood here.
