The imprint of the aragonese construction seems to suggest that dates back to the XV century. The tower is devoid of revenue and it is assumed that for access is used ladders levatoie. The structure, flanked by bastions and towers, was in communication with another castle situated to the north, near Pontoon, of which today have remained only ruins. The name Ziro derives from Siri, tanks dug into the ground and hermetically closed, which was equipped with the tower, or from San Salvatore de Cyrus, a rocky retreat located below the tower. The fame of the construction is related to the story of Joanna the Mad.