Byzantium was never a city-state of great influence like that of Athens, Corinth or Sparta, but the city enjoyed relative peace and steady growth as a thriving commercial city lent by its prominent position.
The site was astride the land route from Europe to Asia and the sea route from the Black Sea to the Mediterranean, and was in the Golden Horn. An excellent and wide port.
Already then, in the Greek and early times of Rome, Byzantium was famous for its strategic geographical position that made siege and capture difficult, and its position at the crossroads of the Asian-European trade route on land and as the gateway between the Mediterranean and the Black Seas, they turned it into a settlement too valuable to be abandoned.