This palace was once the residence of the Bishop and later the Archbishop of Catania. Later it became a monastery and then a seminary. It was destroyed during the earthquake of 1693 and rebuilt. The second (top) floor was added in the late 1800’s. Many illustrious historical figures have appeared from the central balcony, including Cardinal Giuseppe Benedetto Dusmet in 1888 to bless the city. In 1937 Benito Mussolini spoke from it to the citizens during his visit to Catania. Now it houses the Museo Diocesano. To the east of the building and attached to it is the Porta Uzeda.

On the south side of the Piazza del Duomo is a building with an interesting facade, different from the other ones in town. White stone in 'Bugnato Style', where its front part is deliberately given an unpolished, rough surface, contrasting here with walls plastered with black lava sand. Remarquable are also the big windows and the balconies on the first floor, from which the bigger central one was often used by politicians for addressing the populace gathered on Piazza del Duomo. The Seminario is also a work of the general reconstruction of Catania after the great earthquake of 1693, but it was significantly altered about 50 years later. Until the heavy damages by fire during WWII it was a center of learning for clerics. Taken over by the municipality several administrative offices were installed here. Now it serves as the 'Museo Diocesano'. To the east of the building and attached to it is the Porta Uzeda, another landmark of Piazza del Duomo.