An historical and interesting town in the hills south of Cefalù, Castelbuono is part of the Parco delle Madonie and a really beautiful hill town to explore. It has ancient roots (doesn't everything in Sicily?!) going back to the ancient Sicana people who lived here in the 3rd century BC. Then it came under the Greek colony. It saw a Byzantine presence, and bears markings from its Arab-Norman period. The castle was originally built by the Normans. In the 1200s a group of Geracesi moved here (from Geraci). The current name dates to 1329 and an official document filed by the Count Francesco Ventimiglia declaring to the Bishop of Cefalù that he was in possession of the woods and lands of the territory of Castri Boni. The town remained a possession of the Ventimiglia family until 1860.
Of course the very visible crowning feature of town is the castle, built by the Normans originally, then expanded. It has a cube-like Arab style to the main structure, while the corner towers are Norman style, and it was the seat of the Ventimiglia princes for centuries. Inside is the Museo Civico, with artifacts and historical exhibits, as well as contemporary art. A highlight of the castle, though, is the Cappella Palatina di Sant'Anna, a chapel rioutously decorated in Baroque stuccoes. It is, in a word, amazing.
Source: summerinitaly.com