Milazzo's enormous castle was built by Frederick II in 1239 and added to by Charles V of Aragon. It was originally the site of a Greek acropolis, then that of an Arab-Norman citadel. The whole of Milazzo once fit within its huge walls. In 1860, Garibaldi's troops successfully stormed the castle, which was at that time manned by Bourbon soldiers.
The castle grounds contain the city's Duomo Vecchio (old cathedral) and the ruins of the Palazzo dei Giurati (the old town hall). It's a lovely site to clamber around, full of flowers and crumbling walls. To get here, climb the Salita Castello, which rises up through the atmospheric Old Town. Note that at the time of research, the castle's medieval core was closed to visitors due to ongoing restoration work, but the outer perimeter remained open, including the Benedictine monastery and cloisters, the Duomo, and the Aragonese outer walls, which command dreamy views of the bay and the Aeolians.