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Theodosius Harbor
Current Name
Ancient Name
Medieval Name
History of the name

The ancient name of the city , Byzantium ( The place of -Byzas) derived from the name of the leader of Megarans who founded the city on 7th century BC. Afterwards during the 4th century city renamed as Constantinople (the city of- Constantinus)  after the founder of  Byzantine Empire; Constantinus I.   

Place :

Geopolitical Unit
Marmara Region
Administrative subdivision
İstanbul Metropolitan Municipality
Located in northwestern of Turkey within the Marmara region of Turkey. Medieval city is known to be founded on Sarayburnu promontory called as the “historic peninsula” bounded by Golden Horn, a natural harbor dividing the city.
Foudation Date
7th century BC.
Current condition
Istanbul is the largest city forming the economic and cultural center of the country with its population currently more than 12 millions. Being a transcontinental city Istanbul divided by the Bosphorus strait which is one of the world’s busiest waterways crossing between city’s European and Asiatic sides.

The settlement history of the city dates back to Neolithic period. Recent salvage excavations at Istanbul’s Yenikapı district revealed the oldest settlement (ca.6500 BC). at historic peninsula of the city where the ancient and medieval cities were once situated. The prehistoric settlements such as Fikirtepe and Yarımburgaz are also known within today’s Istanbul region.
Prior to the foundation of ancient city, a small village called Lygos founded by Thracian tribes on 13th century BC was situated on Sarayburnu promontory. In 668 BC, Greek colonists from the city of Megara founded a trading colony at the same location. The city’s unique location controlling the waterway linking Black Sea and Mediterranean via Aegean and also serving as the shortest crossing point between Europe and Asia continents, played important role in the development of the city.
The city took over by Persians in 513 BC during the march  famous Persian King Darius’ army towards Thrace. When the Persian army defeated by Spartans in 479 BC the city controlled by Spartans for a short time and then included the Delian League led by Athenians. The city was conquered by Alexander the Great soon after his father Phillip’s unsuccesful siege of Byzantium. By the end of Hellensitic period Byzantium came under Roman control. Afterwards the city involved the Roman civil war by supporting Pescennius against Septimus Severus who emerged victorious from this rivalry. Septimus Severus revenged upon Byzantium by massacring the inhabitants and razing city walls. Considering the city’s strategic position he then reconstructed the walls and enlarged the city.     
By the decline of Roman Empire during the 4th century, the center of the empire was no longer safe as a result of the threat by the northern European tribes. Emperor Constantine proclaimed Byzantium as the new capital on 11 May 330 and rebuild the city according to the Roman model. The city dedicated to be Nea Roma, but soon after it became to be called Constantinople. The empire expanded until the 7th century and the capital was the center of known world at that time. The empire held the control most of the Mediterranean  and Black Sea region. the empire reached its peak during the reign of Justinian who was also the founder of  mighty Haghia Sophia cathedral. He also conducted second largest building programme along Constantinople. However city suffered from plaque epidemic which which caused the loss of one third of the empire’s population. Between 6th and 11th centuries city beseiged several times by Persians, Avars, Arabs and Bulgarians but the city walls none were able to capture the city. In 1204 Crusaders sacked the city and held the control until 1261 when the  Michael VIII Palaeologus retook it.
In 1453 Ottoman siege ended up with the fall of the city and a new period began in the city’s history. Ottoman Empire rebuilt the city and held it until World War I. Today the silhouette of the city contains magnificent examples of Ottoman architecture.


• Haghia Sophia
• Chora Church
• Pammakaristos Church
• Great Palace
• Palace of Constantine Porphyrogenitus
• Boukoleon Palace
• Little Haghia Sophia
• Hippodrome
• Column of Justinian
• Forum of Constantine
• Milion
• Theodosian Land Walls


On 2004 November, Istanbul Archaeological Museums initiated an archaeological salvage excavation project at Yenikapı districts where the main stations of Marmaray and Metro railway hub will be constructed. During the course of fieldwork, this salvage project has turned out to be the most extensive archaeological research in the city’s history. In the largest excavation site of about 58.000 m² at Yenikapı district,  one of the largest harbour of the city in the Early Byzantine period, the Theodosius Harbor/Portus Theodosiacus was revealed. The excavations confirmed that the harbour was established in this former cove, then silted by the Lykos (Bayrampaşa) stream and thereby lying about 300 m from today’s shoreline.      
Theodosian Harbour, namely Portus Theodosiacus, possibly built by Theodosios I (r. A.D. 379-395) in the cove that indents deeply inland (Müller-Wiener: 1998, 8-9). The Sea of Marmara was like a natural harbour formed by a large bay here and the Stream Lykos flowed into here (Fig. 3). With Konstantinopolis becoming the new imperial capital, the trade also increased in parallel to the population. Thus, the capacity of the existing harbours became insufficient and it became necessary to build new harbours or to enlarge the existing ones. The natural deep cove at the mouth of Lykos was enlarged probably in the reign of Theodosios I by building a breakwater in the east-west direction on the south in order to be able to answer the needs of the time. There are various opinions regarding the name and foundation of this harbour in the Byzantine period. The Eleutherios Harbour mentioned in surviving texts is usually accepted to be the forerunner of the Theodosian Harbour and was founded in the reign of Konstantinos I. Another claim is that Eleutherios should be looked for further east. Granaries called Horrea Alexandrina or Horrea Theodosiana, named after Alexandria, Egypt, and the emperor himself were located on the Theodosian Harbour’s east side which was within the Region IX; thus, these suggests that this harbour was used for unloading the grains brought from Egypt and other items and that this was a large commercial harbour. It is known that the grain import continued until 641 when Egypt was conquered by Muslim Arabs. In the beginning the grains were directly transported into the town. The transportation involved large open-sea vessels with high capacities; however, the winds and currents at the Dardanelles, or the Hellespont, constituted a great handicap delaying the transportation; hence it is known that Iustinianos built intermediary depots at island Tenedos (modern Bozcaada) and transportation continued with smaller vessels henceforth to the capital. The harbour proved to have functioned vividly in the transportation of Prokonnesian marble demanded for construction, bricks and tiles, timber and food and beverages. Petrus Gyllius, who stayed in Istanbul from 1544 to 1547 in order to collect ancient manuscripts on behalf of the French king, writes the following about the Theodosian Harbour: « The Theodosian Harbour lied within the vegetable gardens called the Blanka today; it was surrounded with walls all around and located in the flat area on the skirts of the seventh hill along the Sea of Marmara. The harbour’s mouth faced east and a pier extended from this direction toward west. Now on top of these is a fortification wall of 12 feet in thickness extending 600 steps – as I count my steps while walking… Looking at the pier and the location I discovered that the ancient port’s perimeter was more than a mile. At the mouth of the harbour still accessible today is a tower surrounded with the sea and stone debris ». The Theodosian Harbour lost its primary function when the grains transportation from Egypt came to an end toward the middle of the seventh century; however, it continued to serve as a harbour as attested from the shipwrecks uncovered dating from the seventh through the eleventh centuries. The harbour hosted cargo vessels of short distances and fishing boats. It fell out of use in the twelfth century when it was blocked with the silt carried by the Lykos (Bayrampaşa) Stream and was dumped with rubble thereafter. This great harbour was protected from storms with breakwaters. The Byzantine harbours were furnished with high walls built on top of the breakwaters that drew the lines of the inner main port. These walls were usually the extensions of the fortifications on the coastline. The breakwater of the Theodosian Harbour stretched from the Davutpaşa pier on the west, first eastward and then northeast. In the western part of the excavation site, named as Insula 100, was the inner harbour and the excavations here brought to light harbour architecture such as sea walls, pier built with large blocks and the beginning part of the breakwater. The pier, today measuring 25 m. long and 2.80 m. wide, rests on sandy bottom. In the sea bottom deepening toward east before the pier were found about 30 stone anchors following a stratigraphy.Many of the Byzantine port cities had both an inner port and an outer port. Access to the outer port or access to the inner port in case there was no outer port was blocked with iron gates or chains. Similarly the harbours of Thessalonica, Modon and Hierax were closed off with chains. The Golden Horn was also chained off, thus becoming a very large natural harbour . Entrances to the harbours were flanked with towers meant for watching. The entrance to the Theodosian Harbour facing east was guarded by the Belisarios Tower, also known as Belisarios Dungeon or Priest Tower, rising from the middle of the sea. As was the case with other Byzantine harbours, this harbour was also built in two parts surrounded with porticoes as seen in ancient maps.
This tower could have also served as a lighthouse, with its bright light at night, pointing at the presence of a safe shelter nearby. The road leading to the markets of vivid commerce in Byzantine port cities started from the piers and quays inside the harbour. The 43.50 m.-long remains of a pier uncovered in the east part of the Theodosian Harbour indicate to the fact that vessels were loaded and unloaded here. It is known that a crowd gathered on the main pier whenever a vessel sailed to the mouth of the harbour. Many gathered there just out of curiosity to see who the newcomers were and what they brought with them. Longshoremen and other seamen gathered to help the unloading and transporting of the cargo to the storehouses along the piers. On the other hand, ships coming from states with no trade treaties with Konstantinopolis were banned from entering the harbour. It is thought that the silting caused by Lykos filled the western part of the Theodosian Harbour first. When this area, known as the inner harbour, was entirely silted, activities shifted to the east part; however, silting continued and filled the east part starting in the north and progressing toward south. Archaeological excavations have shown that the harbour was almost entirely silted by the end of the twelfth century allowing only small fishing boats and coastal cargo vessels sail into a very small area. The facts that most of the shipwrecks uncovered are dated to the late tenth and early eleventh century and that none date to the later periods further support this hypothesis. The area was known as Vlanga in the Ottoman period and was entirely filled becoming vegetables gardens as understood from the accounts of the travellers. Petrus Gyllius writes the following about the filling of the Theodosian Harbour: « The harbour has been filled, vegetables have been planted in the wide fields and a few arbours have been planted. Fruits hang down from the trees, not sails as Fabios had told; the vegetable gardens are watered from inexhaustible fountains remaining from the ancient harbour.


The great fortification system of the city was first established on 7th century BC enclosing a smaller area where the Topkapı Palace and Haghia Sophia stands today. This wall destroyed by Septimus Severus in 146 BC and soon after rebuilt again. 3rd phase of the fortification realized during the reign of Constantinus I. He enlarged the city walls towards the west. The today’s city walls were built during the reign of Theodossius II (408-450). The fortification system system is about 19 km with 50 gates from Sarayburnu to Yedikule along the Marmara coast, from Yedikule to Ayvansaray and Golden Horn coast. The fortification has been restored several times during the later Byzantine and Ottoman periods and survived to date.       

Medieval Sites

(surviving medieval monuments, visited areas, museums)
• Topkapı Palace Museum
• Hagia Sophia Museum
• Istanbul Archaeological Museums
• Museum of Turkish and Islamic Arts
• Haghia Irene Museum
• Chora Museum
• Istanbul Mosaic Museum
• Rumelihisarı Museum
• Anadoluhisarı Museum
• Yedikulehisarı Museum
• Fethiye Museum (Pammakaristos)

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Visual Material
Writer / Date
Ufuk Kocabaş-Evren Türkmenoğlu, May 2013
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