The ruins overlooking the sea are those of the cathedral and church of St Regulus. All that remains of the former, building of which started in 1318, is the east wall (12C), the west gable (late 13C) and the south wall of the nave. The latter was probably built from 1127 to 1144 to house the relics of St Andrew. Today, from the top of the tower, you can admire a panoramic view of the town. Cathedral Museum boasts a fine collection of early Christian carved stones and a lovely sarcophagus from the 8 or 10C.