La Torre Alfonsina ranks at Porta Terra, the oldest entrance to the old city of the Martyrs. Its realization is due to Alfonso of Aragon, the great liberator of the Turkish occupation city in 1481. The entrance hallway is defended by four "saettiere" overhanging placed on the vault. At the base you can see two inscriptions bearing the name of the tower and a motto which reads SIT FORTITUDO VIRGO MATER MEA (May the Virgin Mother being my fortress).
The great defense system of walls otrantine has been the subject, over the centuries, of many changes. A first plant had to be present already in the Messapian and Roman times. The current route follows part of the city walls built under Byzantine rule, then it rearranged first by Robert Guiscard in 1081 and later by Frederick II nel1228. The continued threats from the sea and the importance of Otranto as Gateway to the East of the peninsula, also brought the Anjou and, later, the Spanish viceroys, to make the walls of the castle and an efficient military architecture. This was possible through the intervention of the best engineers and architects of the military, including Ciro Ciri and Francesco di Giorgio Martini.