The Sea Walls Constantinople
The first seaward walls were ordered built by Constantine I along with the main land wall, and enclosed the city on the sides of the Propontis (Sea of Marmara) and the gulf of the Golden Horn (Chrysoun Keras), but scant information survives regarding them. It is very likely, however, that the later walls followed their course. In 439, after the initial enlargement of the city, Theodosius II ordered the then-Praetorian prefect of the East, Cyrus Panopolites, to extend the old sea walls to encompass the entire city. The construction of the walls was similar to, but simpler than, the Theodosian Walls. It consisted of a single wall, relatively low, as no threat was then expected from the sea, where the Roman navy enjoyed undisputed supremacy.