Constantine Marks Out Constantinople

In AD 324 Constantine defeated his last rival, Licinius, at Chrysopolis, across the Bosporus from the old Greek city of Byzantium, and became sole ruler of the Roman Empire. That same year he chose Byzantium as the site of a new imperial city that would bear his name. It was hard to attack, it commanded the sea passage between the Black Sea and the Mediterranean, and it lay within reach of both the Danube and the Persian frontier.

By tradition the new boundary was laid out in November 324. The walls enclosed an area several times larger than the old town. Constantine brought statues from across the Greek world to adorn it, built a palace, completed the hippodrome and laid out a forum with a great column, and dedicated the city on 11 May 330. Philostorgius, writing about a century later, tells the story of the spear and the unseen guide; whether it happened as he says cannot be known.

Rome remained the ancient capital in name and in memory, but the center of power moved east. After the western empire fell in the fifth century, Constantinople carried the Roman name until 1453.