
The town was for long a mere village, and start its expansion when the Norman Kings of Sicily chose the area as their hunting resort, building here a palace (probably identifiable with the modern Town Hall).
Under King William II the large monastery of Benedictines coming from Cava de' Tirreni, with its church, was founded and provided with a large asset. It is noteworthy that the new edifice had also an important defensive destination. Monreale was the seat of the metropolitan archbishop of Sicily, which thenceforth exerted a large influence over Sicily.
The Cathedral of Monreale is one of the greatest extant examples of Norman architecture in the world. It was begun in 1174 by William II, and in 1182 the church, dedicated to the Assumption of the Virgin Mary, was, by a bull of Pope Lucius III, elevated to the rank of a metropolitan cathedral.