Byzantium or Byzantion (/ bɪˈzæntiəm, bɪˈzænʃəm /; Greek: Βυζάντιον, Byzántion) was an ancient Greek colony in early antiquity that later became Constantinople, and later Istanbul. Byzantium was colonized by the Greeks from Megara in c. 657 BC.
the old greek city-state of byzantium was rebuilt and became known as
Constantinople Istanbul