The tower-prison complex arose from a series of interventions that presumably began between the 15th and 16th centuries. A.D. and ended in the early 19th century A.D. Following the conquest of the island by the Aragonese, the territory of Thiesi, known as the Marquisate of Montemaggiore, was given as a fief to the Manca brothers. These, in order to protect the eastern side of the town, built a tower in a circular shape, with the purpose of protecting the only entrance to the town, which was via the steep staircase coming from the small church of St. John. In the 17th century, with the new Renaissance urban planning ideas, the tower began to lose its primitive and main defensive function: thus, a transformation into a place of detention is not unlikely. It is to this period that the present structure of the tower-prison is dated, with the annexation of some rooms in the front, including a small room with a barrel vault created to house the jailers. In the early decades of the nineteenth century, the Savoy State established the Pretura Mandamentale in the village with the attached Zonal Prison. Again, the complex underwent some structural changes to adapt to its function as a maximum security prison.