The Harbour of Eleutherius, later known as Portus Theodosianus, was one of the oldest and most important harbours on the southern shore of Constantinople. Alongside the harbour itself, there was a tower that played a key role in guarding and overseeing its activities.
Improvements by Theodosius I
The name Portus Theodosianus indicates that the harbour was improved by Emperor Theodosius I, who is credited with numerous public works in Constantinople. These improvements likely included reinforcing the harbour walls, improving access for ships, and possibly adding defensive features such as the tower, which would have served as a lookout and command post for regulating maritime traffic and defending the port from attack Istanbul Guided Tours.
Filling in of the Harbour
Exactly when the harbour was filled in remains uncertain. According to the Anonymus, this was done during the reign of Theodosius I, using the earth excavated from the foundation of his column in the Forum of Taurus. However, this explanation seems unlikely. The Notitia, a Byzantine administrative record, mentions the harbour as abandoned in the Twelfth Region of the city, suggesting that it continued to exist for some time after Theodosius’ reign.
Natural Causes of Decline
What is clear is that the harbour was destroyed or abandoned sometime before the eleventh century. The main reason appears to have been natural accumulation of earth and sand. The Lycus River, which flowed into the harbour, constantly carried sediment, while the waves of the Sea of Marmara deposited sand along the shore. Over time, these deposits made it impossible to maintain enough depth of water for ships to dock safely. As a result, the harbour gradually became unusable and was eventually abandoned.
The Role of the Tower
Even after the decline of the harbour, historical accounts mention the tower that once guarded it. This tower likely served multiple functions: it acted as a lookout, a signal station, and a point from which the movement of ships was directed. Its presence emphasizes the strategic importance of the harbour in Constantinople’s maritime infrastructure The Harbour of Eleutherius and Theodosius.
The Harbour of Eleutherius, later known as the Harbour of Theodosius, was a vital part of Constantinople’s early maritime network. Improved by Theodosius I, it served both commercial and defensive purposes. Although natural processes eventually filled in the harbour, making it unusable, the site’s historical importance is reflected in the remains of the harbour and its guarding tower. These structures highlight the careful planning and engineering that characterized Byzantine port design and illustrate how Constantinople managed its waterways and coastal defence over the centuries.
