What was the original Greek name of the city that became Constantinople? The answer is Byzantium. In Greek, the city was called Byzantion, while Byzantium is the Latinized form familiar in English. It stood on the European shore of the Bosporus, opposite Chalcedon, at a location that controlled access between the Black Sea and the Aegean.
Greek colonists from Megara traditionally founded Byzantion around 657 BCE. Ancient accounts connect its name with Byzas, the legendary leader of the settlers, although the name may have older Thracian or Illyrian roots. The settlement grew into an important trading and strategic center because ships passing between seas had to navigate the narrow strait.
The Roman emperor Constantine the Great rebuilt and greatly enlarged the city, dedicating it as a new imperial capital in 330 CE. It was officially associated with the name New Rome, but Constantinople—“the city of Constantine”—became the usual name. Byzantium remained historically important: modern scholars later used it to form “Byzantine Empire,” even though the empire’s inhabitants generally considered themselves Romans.