Cittadella is a medieval walled city founded in the 13th century as a military outpost of Padua. The surrounding wall has been restored and is 1,461 metres in circumference with a diameter of around 450 metres. There are four gates which roughly correspond the points of the compass.
The town was founded in 1220 by the Paduans to counterbalance the fortification of Castelfranco. It was built in successive stages in a polygonal shape on orthogonal axes through the construction of 32 large and small towers, with the formation of a protective moat and with four drawbridges next to the four entrance gates.
Its walls, 14 to 16 metres tall, were built with the 'box masonry': two parallel walls filled with a sturdy core of stones and hot slaked lime totaling a thickness of about 2.10 metres.
The walls today are all intact except for a stretch destroyed in the 16th century during the Cambrai war, and the skilled detail of the construction are still easily visible. It has as many as seven different construction techniques characterized by the alteration of courses in brick and those in river rocks mixed with brick can be recognized.
Among the elements of interest, the Rocca di Porta Bassano still retains the defense apparatus of the keep and entrance gates. The Casa del Capitano (Captain's House) is found inside the Rocca (Fortress). Restoration has uncovered frescoes dating to the period of the Carraresi, Malatesta, Sanseverino and Borromeo families. They hand down an out-and-out historical account of the events that occurred between 1260 and 1600, almost replacing written documents.
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.