Walls of Constantinople - Land Walls - Theodosian Walls - Construction

Construction

The Theodosian Walls consist of the main inner wall (μέγα τείχος, mega teichos, "great wall"), separated from the lower outer wall (ἔξω τείχος, exō teichos or μικρόν τείχος, mikron teichos, "small wall") by a terrace, the peribolos (περίβολος). Between the outer wall and the moat (σοῦδα, souda) there stretched an outer terrace, the parateichion (τὸ ἔξω παρατείχιον), while a low breastwork crowned the moat's eastern escarpment. Access to both terraces was possible through posterns on the sides of the walls' towers.

The inner wall is a solid structure, 4.5–6 m thick and 12 m high. It is faced with carefully cut limestone blocks, while its core is filled with mortar made of lime and crushed bricks. Between seven and eleven bands of brick, ca. 40 cm thick, traverse the structure, not only as a form of decoration, but also strengthening the cohesion of the structure by bonding the stone façade with the mortar core, and increasing endurance to earthquakes. The wall was strengthened with 96 towers, mainly square but also a few octagonal ones, three hexagonal and a single pentagonal one. They were 15–20 m tall and 10–12 m wide, and placed at irregular distances, according to the rise of the terrain: the intervals vary between 21 and 77 m, although most curtain wall sections easure between 40 to 60 meters. Each tower had a battlemented terrace on the top. Its interior was usually divided by a floor into two chambers, which did not communicate with each other. The lower chamber, which opened through the main wall to the city, was used for storage, while the upper one could be entered from the wall's walkway, and had windows for view and for firing projectiles. Access to the wall was provided by large ramps along their side. The lower floor could also be accessed from the peribolos by small posterns. Generally speaking, most of the surviving towers of the main wall have been rebuilt either in Byzantine or in Ottoman times, and only the foundations of some are of original Theodosian construction. Furthermore, while until the Komnenian period the reconstructions largely remained true to the original model, later modifications ignored the windows and embrasures on the upper store and focused on the tower terrace as the sole fighting platform.

The outer wall was 2 m thick at its base, and featured arched chambers on the level of the peribolos, crowned with a battlemented walkway, reaching a height of 8.5–9 m. Access to the outer wall from the city was provided either through the main gates or through small posterns on the base of the inner wall's towers. The outer wall likewise had towers, situated approximately midway between the inner wall's towers, and acting in supporting role to them. They are spaced at 48–78 m, with an average distance of 50–66 m. Only 62 of the outer wall's towers survive. With few exceptions, they are square or crescent-shaped, 12–14 m tall and 4 m wide. They featured a room with windows on the level of the peribolos, crowned by a battlemented terrace, while their lower portions were either solid or featured small posterns, which allowed access to the outer terrace. The outer wall was a formidable defensive edifice in its own right: in the sieges of 1422 and 1453, the Byzantines and their allies, being too few to hold both lines of wall, concentrated on the defence of the outer wall.

The moat was situated at a distance of about 20 m from the outer wall. The moat itself was over 20 m wide and as much as 10 m deep, featuring a 1.5 m tall crenellated wall on the inner side, serving as a first line of defence. Transverse walls cross the moat, tapering towards the top so as not to be used as bridges. Some of them have been shown to contain pipes carrying water into the city from the hill country to the city's north and west. Their role has therefore been interpreted as that of aqueducts for filling the moat and as dams dividing it into compartments and allowing the water to be retained over the course of the walls. According to Alexander van Millingen, however, there is little direct evidence in the accounts of the city's sieges to suggest that the moat was ever actually flooded. In the sections north of the Gate of St. Romanus, the steepness of the slopes of the Lycus valley made the construction maintenance of the moat problematic; it is probable therefore that the moat ended at the Gate of St. Romanus, and did not resume until after the Gate of Adrianople.

The weakest section of the wall was the so-called Mesoteichion (Μεσοτείχιον, "Middle Wall"). Modern scholars are not in agreement over the extent of this portion of the wall, which has been variously defined from as narrowly as the stretch between the Gate of St. Romanus and the Fifth Military Gate (A.M. Schneider) to as broad as from the Gate of Rhegion to the Fifth Military Gate (B. Tsangadas) or from the Gate of St. Romanus to the Gate of Adrianople (A. van Millingen).