Walls of Constantinople

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, when well manned, they were almost impregnable for any medieval besieger, saving the city, and the Byzantine Empire with it, during sieges from the Avars, Arabs, Rus', and Bulgars, among others (see Sieges of Constantinople). Only the advent of gunpowder siege cannons rendered the fortifications obsolete, resulting in the final siege and fall of Constantinople to the Ottomans on 29 May 1453.

The walls were largely maintained intact during most of the Ottoman period, until sections began to be dismantled in the 19th century, as the city outgrew its medieval boundaries. Despite the subsequent lack of maintenance, many parts of the walls survived and are still standing today. A large-scale restoration programme has been under way in the past twenty years, which allows the visitor to appreciate their original appearance.

The Walls of Byzantium and Constantine

The original fortifications of the city were built in the 8th century BC, when it was founded as Byzantium by Greek colonists from Megara, led by the eponymous Byzas. At the time the city consisted of an acropolis and little more. Byzantium, despite being a prosperous trading post, was relatively unimportant during the Roman period, but featured prominently in the civil war between Septimius Severus and Pescennius Niger, holding out a Severan siege for three years (193-96 AD). As punishment, Severus had the strong walls demolished and the city deprived of its status.[1] However, soon after he rebuilt it, appreciating the city's strategic importance, and endowed it with many monuments and a new set of walls, increasing its area.

When Constantine the Great moved the capital of the Empire to Byzantium, which he refounded as Nova Roma, he greatly expanded the new city by building a new wall about 2.8 km (15 stadia) westwards of the Severan wall and incorporating even more territory.[2][3] Constantine's fortification consisted of a single wall, reinforced with towers at regular distances, which began to be constructed in 324 and was completed under Constantine II. The approximate course of the wall is known, running from the area of the Plateia Gate of the Golden Horn sea walls to near the Gate of St. Aemilianus on the Propontis walls (see section on the Sea Walls below). The wall survived during much of the Byzantine period, even though it was replaced by the Theodosian Walls as the city's primary defence; however, only the Old Golden Gate still survived to late Byzantine times, until destroyed by an earthquake in 1509. Already by the early 5th century however, Constantinople had expanded outside the Constantinian Wall, in the extra-mural area known as the Exokionion.

The Theodosian Walls

Restored section of the Theodosian Walls at the Selymbria Gate. The Outer Wall and the wall of the moat are visible, with a tower of the Inner Wall in the background
Restored section of the Theodosian Walls at the Selymbria Gate. The Outer Wall and the wall of the moat are visible, with a tower of the Inner Wall in the background

In 408, during the reign of Emperor Theodosius II, construction began on a new wall, about 1,500 m to the west of the old, which stretched for 5,630 meters between the Sea of Marmara and the suburb of Blachernae near the Golden Horn. The new wall, which became known as the Theodosian Wall (Greek Theodosianon Teichos), was built under the direction of Anthemius, the Praetorian prefect of the East, and completed in 413.[6] New Rome now enclosed seven hills and justified the appellation Eptalofos, like Old Rome. On November 6, 447, however, a powerful earthquake destroyed large parts of the wall, and Theodosius II ordered the urban prefect Cyrus of Floros (sometimes referred to as Constantine) to supervise the urgent repairs, as the city was threatened at the time by Attila the Hun. Cyrus employed the city's dēmoi (more widely known as "Circus factions") in the work, and succeeded in restoring the walls within 60 days, as testified in two inscriptions in Greek and Latin on the Mevlevihane Gate. At the same time, a second outer wall was added, and a wide ditch opened in front of the walls.

The Second Military Gate or Gate of Belgrade

The walls were built of alternating layers of stone and brick in two lines of defense which adjoined the ditch. The Inner Wall (Esō Teichos or Mega Teichos, "Great Wall") was a solid structure, 5 metres thick and 12 metres high. It was strengthened with 96 towers, mainly square but also octagonal or hexagonal, 18-20 metres tall, every 55 metres.[8] Each tower had a battlemented terrace on the top. Its interior was usually divided by a floor in two chambers. The lower chamber, which opened 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.[9] The Outer Wall (Exō Teichos or Proteichisma) was built 15-20 metres from the main wall, creating a space between the two walls called perivolos. The Outer Wall was 2 metres thick at its base, and featured arched chambers on the level of the perivolos, crowned with a battlemented walkway, reaching a height of 8.5 metres. 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 96 towers, square or crescent-shaped, situated in the middle distance between the Inner Wall's towers. They featured a room with windows on the level of the perivolos, crowned by a battlemented terrace, while their lower portions were either solid or featured small posterns, which allowed access to the outer terrace. The moat (souda) was situated at a distance of about 15 metres from the Outer Wall, creating a terrace called parateichion, where a paved road ran along the walls' length. The moat itself, which could be flooded, was about 20 metres wide and 10 metres deep, featuring a 1.5 metre tall crenellated wall on the inner side, serving as a first line of defence.

Detailed course and description of the Land Walls (from south to north)

The walls stretched for about 5.5 km from south to north, from the Marble Tower, Turkish Mermer Kule (or "Tower of Basil and Constantine") on the Propontis coast to the Blachernae, ending at about the area of the Palace of Porphyrogenitus (known in Turkish as Tekfur Saray), where they adjoined the later walls of Blachernae. The wall contained 10 main gates, plus an unknown number of small posterns, which were usually walled up in the event of a siege. The five public gates led across the moat on bridges, while the five so-called "Military Gates", known initially only by their numbers, led to the outer sections of the walls. In order, from south to north, these gates were:

• the First Military Gate (Pylē tou Prōtou), or Gate of Christ, named so because of the Chi-Rō Christogram inscribed on it, today known as the Tabak Kapi.
• the Golden Gate (Greek Chrysē Pylē, Latin Porta Aurea, Turkish Altinkapi or Yaldizlikapi), which was a triumphal arch from the reign of Theodosius I, originally standing alone, outside the Constantinian Wall, over the Via Egnatia. It was incorporated in the Theodosian Walls, serving as the state entrance into the capital, especially for the occasions of a triumphal return of victorious emperors from battle.[14] It was architecturally elaborate, built of large square blocks of polished marble fitted together without cement, with three arches. During later years, two great flanking towers of the same material were added. Upon the gates were placed sculpted bronze elephants, flanked by winged Victories. Behind the gate lies the Ottoman-era Yedikule Fortress (see below). Since the main Gates were usually kept closed, a smaller gate exists after the Fort, the Small Golden Gate (Mikra Chrysē Pylē), modern Yedikule Kapisi, which was used for everyday traffic.
• the Second Military Gate (Pylē tou Devterou), the greatest of the military gates. Its is known today as Belgrade Gate (Belgrad Kapisi), after the Serbian artisans settled there by Sultan Suleyman the Magnificent after he conquered Belgrade in 1521.
• the Gate of Melantias (Porta Melantiados) or Selymbria Gate (Turkish Silivri Kapisi), also known as Zōodochos Pēgē after a monastery outside the Walls, where the forces of the Empire of Nicaea under General Alexios Strategopoulos entered and retook the city from the Latins on 25 July 1261.
• the Third Military Gate (Pylē tou Tritou) at the section known as the "Sigma", today walled up.
• the Gate of Rhegium (Pylē Rēgiou), modern Yeni Mevlevihane Kapisi, also named Pylē Rousiou ("Gate of the Reds"), because it had been repaired in 447 by the dēmos of the Reds.
• the Fourth Military Gate (Pylē tou Tetartou), south of modern Millet Jaddesi.
• the Gate of St. Romanus (Porta Agiou Rōmanou), named so after a nearby church, is called Topkapi, the "Cannon Gate" today, because of the great cannon (the "Basilic") that was placed opposite it during the last siege of Constantinople. Emperor Constantine XI established his command here, at the central and most threatened stretch of the walls.
• the Fifth Military Gate (Pylē tou Pemptou), called Hüjum Kapisi, the "Assault Gate", in Turkish, because there the decisive breakthrough was achieved on the morning of May 29, 1453.
• the Gate of Charisius (Porta Charisiou) or Polyandrion (Porta Polyandriou, named so because it led to a cemetery outside the Walls), in Turkish Edirnekapi ("Gate of Adrianople"), where Mehmed II made his triumphal entry into the conquered city. This gate stands on top of the sixth hill, and was the highest point of the city at 77 metres.

At the very end of the Theodosian Walls is the postern called the Xylokerkos Porta or Kerkoporta, after a wooden circus (amphitheatre) that existed there. This gate was left open on the fateful 29 May, apparently accidentally but possibly through treachery, and through it the Janissaries first entered the city. A large plaque today marks the spot.

The restored Gate of Charisius or Adrianople Gate, where Sultan Mehmed II entered the city.

The stretch of walls between the Gate of St. Romanus and the Gate of Charisius, with a length of 1,250 metres, was known as the Mesoteichion ("Middle Wall"). It was considered as the weakest part of the walls, because the ground descended towards the valley of the Lycus River, and as a result the walls lay lower than the opposing slopes. It was here that Mehmed II had placed most of his artillery, and as a result, much of this portion of the walls lies still in ruins today.

The impression made by the mighty Theodosian Walls on the Western Crusaders who encountered them can be seen in the 13th century Caernarfon Castle in Wales, built by Edward I of England as a royal residence, which is said to have been modelled on them. With the advent of siege cannons, however, the fortifications became obsolete, but their massive size still provided effective defence, as demonstrated during the Second Ottoman Siege in 1422. In the final siege, which led to the fall of the city to the Ottomans in 1453, the defenders, severely outnumbered, still managed to repeatedly counter Turkish attempts at undermining the walls, repulse several frontal attacks, and restore the damage from the siege cannons for almost two months. Finally, on 29 May, the decisive attack was launched, and when the Genoese general Giovanni Giustiniani was wounded and withdrew, causing a panic among the defenders, the walls were taken. After the capture of the city, Mehmed had the walls repaired in short order among other massive public works projects, and they were kept in repair during the first centuries of Ottoman rule.

Many sections were restored during the 1980s, with financial support from UNESCO, but the restoration programme has been criticised for focusing on superficial restoration and poor quality of work, which became apparent in recent earthquakes, as well as destroying historical evidence. [16] Nonetheless, the restored sections give a fairly accurate image of the walls as they stood during Byzantine times. The wall runs through the suburbs of modern Istanbul, with a belt of parkland flanking their course. The walls are pierced at intervals by modern roads leading westwards out of the city.