According to tradition, it was founded by the Byzantines between the 8th and 9th centuries and renamed by the Arabs Qalʿat-an-Nisāʾ (“fortress of women,” from which the city’s toponym would derive). The fortress became a strategic stronghold in the Norman era, visually connected with the towers of Pietraperzia, Sabucina, and Capodarso. Medieval chronicles recall it as the stage of sieges during the Sicilian Vespers, of the baronial conclaves that in 1358 divided Sicily among the Four Vicars, and, in 1407, of its passage to the powerful Moncada family, who held the fief until the abolition of the feudal system. Its sudden ruin came on the night of February 27, 1567: a violent collapse of the gypsum bank brought down bastions, armories, and part of the keep; only two polygonal towers and stretches of wall remained standing, later reused as a stone quarry for city construction.
Even today, walking among the blocks of calcarenite sprinkled with red lichens—hence the name “pietra rossa”—you can still see splayed arrow slits, a section of the wall-walk, and the base of the cistern, while the view embraces the entire Nissena basin up to the Capodarso bridge. At dusk, grazing lights ignite the jagged curtains and lead the visitor toward the nearby Sanctuary of the Lord of the City, built on the southern embankment. Popular legends tell of a fiery horse that emerges from the ruins every night of St. John, guardian of a treasure buried by the Moncadas, and of the ghost of Princess Adelasia, niece of King Roger, whose spirit roams among the ruins of the castle in search of her lost love.
Today the site is a must-see for those who wish to capture the medieval soul of Caltanissetta: a balcony suspended between history, myth, and silence, where the reddened ruins converse with the clear sky of inland Sicily and remind us of the fragility of every power in the face of the earth’s relentless force.