ISTANBUL FORTIFICATION WALLS

Istanbul - Turkey

The Walls of Constantinople are a series of stone walls that have surrounded and protected the city of Constantinople since its founding as the capital of the Eastern Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they are one of the greatest and most complex fortification systems ever built.

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.

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.

LAND WALLS

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. 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.

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 backgroundIn 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. 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 demoi (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.

Construction
The walls were built in two lines of defense, which adjoined the ditch. The main Inner Wall (Esō Teichos or Mega Teichos, "Great Wall") is a solid structure, 5 metres thick and 12 metres 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 walls were built of alternating layers of stone and brick in two lines of defense which adjoined the ditch. The Inner Wall (Eso 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.

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.

The Outer Wall (Exo 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.

The walls stretched for about 5.5 km from south to north, from the Marble Tower, Turkish Mermer Kule (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 :

1. The First Military Gate, or Gate of Christ, named so because of the Chi-Ro Christogram inscribed on it, today known as the Tabak Kapı.

2. The Golden Gate (Turkish Altınkapı or Yaldızlıkapı), 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. 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. Since the main Gates were usually kept closed, a smaller gate exists after the Fort, the Small Golden Gate, modern Yedikule Kapısı, which was used for everyday traffic.

3. The Second Military Gate, the greatest of the military gates. Its is known today as Belgrade Gate, after the Serbian artisans settled there by Sultan Suleyman the Magnificent after he conquered Belgrade in 1521.

4. The Gate of Melantias or Selymbria Gate (Turkish Silivri Kapısı), also known as Zoodochos Pege 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.

5. The Third Military Gate at the section known as the "Sigma", today walled up.

6. The Gate of Rhegium, modern Yeni Mevlevihane Kapısı, also named "Gate of the Reds", because it had been repaired in 447 by the demos of the Reds.

7. The Fourth Military Gate, south of modern Millet Caddesi.

8. The Gate of St. Romanus, named so after a nearby church, is called Topkapı, the "Cannon Gate" today, because of the great cannon 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.

9. The Fifth Military Gate, called Hücum Kapısı, the "Assault Gate", in Turkish, because there the decisive breakthrough was achieved on the morning of May 29, 1453.

10. The Gate of Charisius or Polyandrion (named so because it led to a cemetery outside the Walls), in Turkish Edirnekapı "Gate of Adrianople", where Sultan 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.

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, Sultan Mehmed II 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.

The Yedikule Fortress
The first fortress behind the Golden Gate began being built during the reign of John I Tzimiskes and was completed under Manuel I Komnenos. That fort (Kastellion) had five towers, and was hence also named Pentapyrgion. It was destroyed after the first fall of the city to the Fourth Crusade, and rebuilt only in 1350 by John VI Kantakouzenos.

The new fort featured five octagonal towers, and together with the two marble towers of the Golden Gate, seven in total, becoming known as the Eptapyrgion "Seven Towers". In 1391 however, John V Palaiologos was forced to raze the fort by Sultan Bayezid I, who otherwise threatened to blind his son Manuel, whom he held captive. Emperor John VIII Palaiologos attempted to rebuild it in 1434, but was thwarted by Sultan Murad II.

After the final capture of Constantinople, Sultan Mehmed II rebuilt the fort in 1457, again with seven towers (four on the Inner Theodosian Wall - towers eight to eleven - and three larger ones behind), as the Yedikule Hisar (Turkish for "Fortress of Seven Towers"). During much of the Ottoman era, it was used as a treasury and state prison. Amongst its most notable prisoners was the young Sultan Osman II, who was imprisoned and executed there by the Janissaries in 1622.

The Walls of Blachernae
In the northwestern corner of the city, the suburb of Blachernae with its important church of Panagia Vlacherniotissa was left out of the Theodosian walls. To defend it, in the face of the great Avar siege, a single wall was built, around 627, in the reign of Heraclius. In 814, Leo V the Armenian built a new wall in front of the Heraclean one to safeguard against Bulgarian raids.

In the 12th century, when Blachernae had become the favoured imperial residence, Manuel I Komnenos built a wall, starting from the end of the Theodosian Walls, to protect the imperial palaces, which was connected by a later wall (possibly under Isaac II Angelos) to the Heraclean wall. Despite all this, the defences of the Blachernae section remained weaker than at the Theodosian Walls, and it was here the Crusaders of the Fourth Crusade managed to penetrate them and first enter the city.

The Walls of Blachernae consist of four single walls built in different periods. Generally they are about 12-15 metres in height; thicker than the Theodosian Walls and with more closely spaced towers, while lacking a moat. The fortification begins at the end of the Theodosian Walls with the Komnenian Wall, connected by the Angelian wall to the Heraclean wall, which in turn is connected to the Sea Walls at the Golden Horn. The wall of Leo V lies in front of the Heraclean wall.

The wall of Manuel Komnenos is an architecurally-excellent fortification, extending for 220 m, with 9 towers, the small gate (paraportion) of St. Kallinikos between the second and third towers, and one gate after the sixth tower, the modern Eğri Kapı "Crooked Gate", which is identified with the old Kaligaria Pyle, the "Gate of the Bootmakers' Quarter". The Eğri Kapı is so named because the road in front of it detours sharply around a tomb, which is supposed to belong to Hazret Hafiz, a companion of the Prophet Muhammad, who died there during the first Arab siege of the city.

The Komnenian wall ends at the third tower from the gate, and the newer wall (from the late 12th century), architecturally much inferior, continues for ca. 400 metres. This wall has four square towers and a gate, the Gyrolimne Gate (from Argyre Limne, the "Silver Lake") between the second and third of them, now walled up, which led to the Blachernae Palace.

The last stretch of the wall is adjoined by two structures: the Tower of Isaakios Angelos, built around 1188 as a residence for the Emperor, and the nearby building and tower known as Prisons of Anemas, dated to the 7th century but named after Michael Anemas, a general of Alexios I who was imprisoned there after a failed plot against the Emperor.

The wall of Heraclius begins from there and extends for about 100 metres to the Sea Walls. It has three strong hexagonal towers, and the Gate of Blachernae (Pyle Vlachernon). The wall of Leo V complements it from the outside, forming a sort of rectangular fort, with an internal space of ca. 25 metres between the two walls. At the edge of the Leontian wall stands the Tower of St. Nicholas, originally built by Leo V and rebuilt by Emperor Romanus I Lecapenus.

The Leontian Wall is thinner and of inferior construction to the Heraclean, and features four small towers along with a now collapsed gate, which formed the outer counterpart of the Blachernae Gate. Since the Sea Walls at the Golden Horn were built at a distance from the shore, a wall extended from the end of the Land Walls to the shoreline, the so-called Vrakhiolion, erected at the same time as the main Heraclean wall, in 627. It had a single gate, the "Wooden Gate" (Xyloporta).

Preservation of the Walls
The land walls run through the suburbs of modern Istanbul, with a belt of parkland flanking their course. They are pierced at intervals by modern roads leading westwards out of the city. Many sections were restored during the 1980s, with financial support from UNESCO, but the restoration programme has been criticised for destroying historical evidence, focusing on superficial restoration, the use of inappropriate materials and poor quality of work.

This became apparent in the 1999 earthquakes, when the restored sections collapsed while the original structure underneath remained intact. The threat posed by urban pollution, and the lack of a comprehensive restoration effort, prompted the World Monuments Fund to include them on its 2008 Watch List of the 100 Most Endangered Sites in the world. The biggest risk to their survival is the lack of a comprehensive plan to guide their long-term preservation and interpretation.

The conditions of the walls were among the factors that led to the consideration of the Historic Areas of Istanbul - a World Heritage Site - for inclusion in the List of World Heritage in Danger in 2006. The UNESCO committee decided, however, to allow the Turkish government more time to develop conservation strategies for the walls before placing Historic Istanbul on the World Heritage List in Danger. It is hoped that Watch listing will help to encourage this effort and highlight the importance of saving the walls.

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