Byzantium

Byzantium was an ancient Greek city founded around 667 BC by colonists from Megara at the entrance to the Black Sea, on the site of what is now Istanbul's Fatih district. Defensible on nearly all sides by water, it grew into a major trading hub controlling the passage between the Mediterranean and Black Sea and remained primarily Greek speaking for over two thousand years; Emperor Constantine I refounded it as an imperial residence in 330 AD, renaming it Nova Roma and then Constantinople, and it eventually became Istanbul after the Ottoman conquest of 1453.