The cathedral has a Latin cross groundplan, with a nave and two aisles. In the southern aisle are the baptistery and, at the first altar, a canvas of Saint Febronia of Nisibis by Borremans facing, on a pilaster, the tomb of the composer Vincenzo Bellini. Also on a pilaster between this aisle and the nave is the Baroque monument of Bishop Pietro Galletti. Also notable is the Chapel of St. Agatha. The apse dates back to the original 12th-century construction: it features a medieval mullioned window and a late-16th-century choir by the Neapolitan artist Scipione di Guido. At the end of the north transept is the Chapel of the Holy Crucifix, by Domenico Mazzola (1577). It houses the tombs of members of the Aragonese branch of Sicily, including Kings Frederick III and Louis, John of Randazzo, and Constance. The northern aisle has several 17th-century paintings of saints, including one by Borremans.