Originally the 13th-century fortress of Naples' French ruler Charles d'Anjou, it was rebuilt in the 15th century as a palace for the Spanish kings of Aragon.
In Naples, the 13th-century fortress was under French rule but it was built again in the 15th century as a palace for Spanish rulers. 
mnli hypothesis: In Naples, the 13th-century fortress was under French rule but it was built again in the 15th century as a palace for Spanish rulers.  premise: Originally the 13th-century fortress of Naples' French ruler Charles d'Anjou, it was rebuilt in the 15th century as a palace for the Spanish kings of Aragon.