The Harbour of Eleutherius, later known as the Harbour of Theodosius, was one of the most important harbours on the southern coast of Constantinople. Its dimensions, construction, and defensive features reveal the careful planning and engineering of the Byzantine city.
Size and Dimensions
The harbour measured approximately 786 yards from east to west and 218 yards from south to north. Its southern side and part of the eastern side were protected by a mole—a long structure built into the sea for protection—measuring twelve feet thick. The mole was carefully constructed of masonry to withstand the waves and to defend the port from attack Tower Guarding the Harbour of Eleutherius and Theodosius.
The mole extended from the Gate of St. Emilianus (Daoud Pasha Kapoussi) eastwards for about 436 yards, then turned northwards for another 327 yards. On most of the mole, walls were built to provide military defense, ensuring that the harbour remained secure against enemy ships.
Harbour Entrance
The harbour’s entrance was located at the north-eastern end, between the tip of the mole and the site of the Gate Yeni Kapou, where today the Roumelian Railway runs. A tower stood a short distance out in the sea, guarding the entrance and monitoring all ships entering or leaving the harbour. This tower highlights the strategic importance of the harbour as a controlled and defended port.
The Quarter of Eleutherius
The area surrounding the harbour was known as the quarter of Eleutherius. Historical records mention this quarter under the same name as late as 1203, during the catastrophic fire caused by the Crusaders, which destroyed much of the city. The harbour and its quarter marked the farthest point reached by this fire, illustrating both the size of the urban area and the harbour’s location at the city’s edge.
Over time, the name of the quarter changed to Vlanga, reflecting the Turkish period of the city’s history. Despite these changes, the physical remains of the harbour, mole, and defensive walls provide a clear record of its original size, structure, and function Daily Istanbul Tours.
The Harbour of Eleutherius was a large, well-defended port crucial to Constantinople’s maritime and military activities. With its mole, entrance tower, and fortified walls, it was designed to protect ships, regulate traffic, and resist enemy attacks. Its location in the quarter of Eleutherius (Vlanga) placed it at the southern edge of the city, near other key harbours and landmarks. Even centuries later, the remains of the harbour and its surrounding structures reveal the advanced engineering and strategic planning of the Byzantine Empire.
