The Harbour of Kaisarius and the Neorion at the Heptascalon were important ports on the southern shore of Constantinople, along the Sea of Marmara. Historical evidence from Nicephorus Gregoras provides detailed clues about their location and connection to other harbours in the city.
Evidence from Nicephorus Gregoras
Gregoras notes that the harbour was situated where the city walls were protected by boulders. These boulders acted as a breakwater, safeguarding ships against strong waves from the Marmara Sea. Ships leaving the harbour during a south wind could sail directly to the Bosporus, while vessels coming from the Bosporus passed Chalcedon on the left. Observers at Chalcedon could watch ships arrive at the harbour, which highlights the strategic placement of this port for both defense and naval operations Guided Istanbul Tour Whirling Dervishes.
These facts indicate that the harbour could only have been located on the Marmara side of the city, not on the Golden Horn or other northern shores. Its orientation allowed the Byzantines to control naval access to the southern approach of Constantinople while keeping watch over enemy movements from the Asiatic coast.
Relationship to Other Harbours
Given that the Harbour of Kaisarius and the Neorion at the Heptascalon were on the Marmara side, the next question is whether they still existed as separate harbours or were merely different names for harbours already known.
The area suitable for additional harbours was limited. The only flat ground capable of hosting a new port lay at the foot of the Third Hill, stretching from the Kontoscalion at Koum Kapoussi to the Harbour of Theodosius at Vlanga, a distance of approximately 910 yards. The rest of the coastline was either too steep or unsuitable for construction, making it impossible to place another harbour elsewhere on this side of the city.
Therefore, if the Harbour of Kaisarius and the Neorion at the Heptascalon were not simply alternative names for known harbours like the Kontoscalion or Theodosius, they must have been located in the space between Koum Kapoussi and Vlanga. This area was large enough to accommodate two separate harbours while maintaining the strategic and navigational requirements needed for trade and naval defense The Neorion at the Heptascalon and Its Location.
The Harbour of Kaisarius and the Neorion at the Heptascalon were undoubtedly located on the Sea of Marmara side of Constantinople. Evidence from Gregoras regarding breakwaters, ship movements, and visibility from Chalcedon confirms their southern location. The limited flat coastline between Koum Kapoussi and Vlanga represents the only feasible area for these ports, whether as distinct harbours or as alternative names for previously identified ones. These harbours played a crucial role in trade and naval operations, ensuring that Constantinople’s southern approach remained both accessible and defensible.
