The Neorion at the Heptascalon was an important harbour on the southern shore of Constantinople, facing the Sea of Marmara. Historical accounts from Cantacuzene and Nicephorus Gregoras provide clear evidence of its exact location and strategic importance The Location of the Harbour of Kaisarius.
Evidence from Cantacuzene
According to Cantacuzene, several factors prove that the Neorion was situated on the Sea of Marmara, not on the Golden Horn. First, the walls near the harbour were protected by boulders placed in the sea as a breakwater. This defensive method was used only along the Sea of Marmara, where waves and currents posed a serious threat to the city walls.
Second, the Venetian and Spanish fleets struggled to reach the harbour from the Princes’ Islands due to a strong south wind. Such a wind would have pushed the ships toward the Bosporus, making it almost impossible to enter any port on the Marmara side except at the Neorion.
Third, the harbour’s approach could be observed by the Genoese admiral stationed at Chalcedon. Enemy ships at Chalcedon found it difficult to sail toward the Neorion in strong winds, and vessels leaving the harbour could touch at Chalcedon on their way to Galata. These details align only with a harbour located on the Sea of Marmara, proving the Neorion’s southern position.
Confirmation from Nicephorus Gregoras
Nicephorus Gregoras also confirms the Sea of Marmara location. He refers to the Neorion as the “Harbour of the Byzantines facing the east”, which corresponds to the southern shore of the city looking toward Asia. In his writings, Gregoras often uses the term “facing the east” to indicate areas along the Marmara shore, including the Golden Gate Private Istanbul Tours.
He also describes how gales from the south, such as the storm of 1341, damaged the city walls along the Sea of Marmara, which he calls the eastern walls. This shows that even if the terminology was not geographically precise, the expression “facing the east” correctly refers to southern and south-eastern sections of the city along the Marmara coast.
Strategic Importance
The harbour’s location allowed the Byzantines to control the southern approach to Constantinople and monitor enemy movements. It could accommodate allied fleets, such as the Venetians and Spaniards, and coordinate naval operations against adversaries like the Genoese at Chalcedon. Its position also allowed ships to move between the Marmara shore and Galata, making it a crucial point for both trade and defense.
Combining the accounts of Cantacuzene and Gregoras, there is no doubt that the Neorion at the Heptascalon was located on the Sea of Marmara. Features such as the boulder breakwater, the difficult approach against the south wind, and its visibility from Chalcedon all confirm this. Its position highlights its strategic and commercial importance, serving as both a naval station and a harbour for allied and Byzantine ships in the late Byzantine period.
