It was constructed by order of Byzantine Emperor Justinian (r. 527–565), made of large moles of black stone.
The Harbor of Eutropius was placed east of Chalcedon (modern-day Kalamış), along the coast of Asia Minor in lands possessed by the Byzantine Empire.
At the time of its construction, there was no permanent land connection between Constantinople and its Asia Minor counterparts, a situation which continued until 1973, when the Bosphorus Bridge was completed.
[6] The Byzantinist Klaus Belke has suggested it was a tertiary harbor for Chalcedon or may have primarily served to supply the imperial summer palace at Hieria.
[4] Due to the recent growth of the maritime districts of Kalamış and Fenerbahçe, nothing remains of the Harbor of Eutropius.