The building was erected soon after the foundation of the town, following the licentia populandi of 1597, along with the construction of churches and dwellings. The two-story building housed prisons, the pantry, and granaries on the ground floor, while the noble floor accommodated the residence of the baron or his governor, since the baron himself resided in Palermo. The structure has undergone many transformations since its construction. In 1740, the Prince’s granary, built against the northern façade, concealed much of the main front that once overlooked the large Piazza Vecchia, leaving visible only a portion with two fine early 17th-century windows, still intact. Due to inheritance divisions, the building underwent several alterations starting from the late 18th century, which changed its original appearance. The architectural style, where preserved, is consistent with that adopted in the post-medieval period in noble palaces of feudal lords. Two façades are visible, with a large corner buttress, facing Piazza Castello; the southern façade, adjoining the very narrow Vicolo Castello, where there remains a portal that may have corresponded to the entrance of the prisons and which closes to the east with a sloping wall, the only remnant of the original structure, built with large corner blocks; and the less altered façade facing Via Municipio, with the central doorway surmounted by a pointed arch window with wrought-iron protection. On this side, the façade is crowned by an elegant terracotta cornice that reveals the presence of a terrace. The presence of the sloping wall has led some to hypothesize that this was a remnant of the ancient Statio Petiliana, as can be read on some websites, but in reality, no study has confirmed construction methods attributable to the Romans.