With medieval characteristics, Caminha castle was built on military foundations of the 4th and 5th centuries. The defences were reinforced and expanded during the Christian Reconquest. During conflicts with Castile, its settlement and defense were encouraged under the reigns of King Afonso III (1248-1279), King Denis (1279-1325) and John I (1385-1433), due to the strategic value that this lindeira town represented for the kingdom.
With the closure of the 1383-85 Portuguese interregnum crisis, the village supported John. The new King John I helped the village and garrisoned by a second line of walls. Under the reign of King Manuel I (1495-1521), the town and its castle are recorded in drawings by Duarte de Armas in his Book of Fortresses, c. 1509.
The current Clock Tower (Torre do Relógio) would be the most important and robust building of the fortified ensemble, originally constituted as the Keep, with a quadrangular shape and an inscription of regal arms stone. Since the beginning of the 17th century it houses the village clock, the bell dating from 1610, and since the Restoration War it bears a stone image of Our Lady of Conception.
References:The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.