Arechi castle was built on Mount Bonadies, which is 300 metres above sea level and dominates the town from the north forming a triangular defensive system. The castle attained military importance in the 8th Century, during the reign of the Lombard Prince Arechi II, who extended and rebuilt it to the standards of Roman and Byzantine times. It was considered a strategic position for the town on the Mediterranean coast and an excellent access both for commercial and for defensive purposes, hence the fortification of the old Salernum, which became Capitol of the Benevento Duchy.
