After the naval victory at Cyzicus, in 408 BC the Athenian general Alcibiades probably built a custom station for ships coming from the Black Sea on a small rock called Arcla (small castle) and Damialis (its calf) in front of Chrysopolis (today's Üsküdar).
In 1110 Byzantine Emperor Alexius Comnenus built a wooden tower protected by a stone wall.[3] From the tower an iron chain stretched across to another tower erected on the European shore in the Mangana quarter of Constantinople.[3] The islet was then connected to the Asiatic shore through a defence wall whose underwater remains are still visible.[3] During the Ottoman conquest of Constantinople in 1453, the tower held a Byzantine garrison commanded by the Venetian Gabriele Trevisano.[3] Subsequently, the structure was used as a watchtower by the Ottomans during the reign of sultan Mehmed the Conqueror.