The Cathedral was completed in 1185. Several additions, alterations and numerous restorations have modified the original aspect, which is characterized by a variety of architectural styles. In the main facade there is a fourteenth century porch in Gothic-Catalan style. The dome kow ever is in a late baroque style, while the apse with its Arab-Norman decorations is the most ancient part. The interior was rebuilt in neo-classical style during the XIX century on the basis of a project by Ferdinando Fuga with a Latin cross plan and three aisles.
Inside the Cathedral is a royal pantheon, sheltering many tombs of kings of Sicily, Frederick II and Roger II among the others, as well as, the tomb of St. Rosalia, the patron saint who saved the town from a plague. In the Treasury is a gold tiara owned by Costance of Aragone as well as other precious objects, which were founded in the royal sepulcher.
