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 15th-century Maestro di Castelsardo. More of his works can be seen in the Museum Ampuriense in the crypt.
A series of small rooms chiselled out of the living rock, the crypt is all that remains of the Romanesque church that once stood here.