Cefalù, town and episcopal see, northern Sicily, Italy. It lies at the foot of a 1,233-foot (376-metre) promontory along the Tyrrhenian Sea, east of Palermo city. It originated as the ancient Cephalaedium, which was probably founded as an outpost of the Greek city of Himera and first appeared in history about 395 bce as an ally of the Carthaginian leader Himilco. Valued for its strategic position on the height of the promontory, the ancient town was in turn conquered by the Syracusan tyrants Dionysius I and Agathocles and by the Carthaginians, from whom the Romans seized it in 254 bce. A new town was founded at the foot of the promontory by the Norman king Roger II in 1131 ce, the year in which Cefalù’s famous cathedral was begun. The exterior of the cathedral is well preserved, with massive four-story towers on each side of the facade. The cathedral’s interior was considerably restored in the 16th and 17th centuries. The Byzantine-style mosaics in the apse and in the first spaces between the arches of the choir (1148) are among the most beautiful in Sicily. Among ancient remains in the area are included the so-called temple of Diana, a pre-Hellenic sanctuary of megalithic construction (9th or 8th century bce) on the promontory site of the ancient city, and portions of a megalithic wall dating from the 6th century bce. The Mandralisca Museum contains archaeological and art collections.

A port and road and rail junction, Cefalù is a tourist centre. Grapes, olives, and citrus fruits are cultivated. Fishing is important, and there is a canning industry. Pop. (2006 est.) mun., 13,716.