The castle reveals layers of local history. Located just outside the old city, it showcases four main historical phases. Roman excavations on-site testify to the earliest period. The second part was likely built in 1132 by the Norman king Roger II and was rebuilt in 1233 by Frederick II, Emperor of the Holy Roman Empire. Later, it was acquired by Duke Ferdinand of Aragon and donated to the Sforza family, who added the watchtowers in the 16th century. Finally, under the King of Naples in the 17th century, the structure was converted into a prison and soldiers’ quarters. Today, the castle houses exhibitions, including Romanesque-era plaster casts collected from across the province.