Before Istanbul, before Constantinople: Byzantium. And an ancient joke about it says the people across the water must have been blind.
Greeks from Megara settled the Asian shore first: Chalcedon, today's Kadıköy. Later Greeks founded Byzantion opposite, on Sarayburnu; legend names the leader Byzas. When? About 667 BC by Herodotus's count, 656 by Eusebius.
Two jokes. Keep them straight.
Joke one is Herodotus. Around 513 BC Persia took Byzantium; Darius left a general, Megabazus, in command in Europe. At Byzantium he learned the Chalcedonians had settled 17 years before the Byzantines, and said they must have been blind to take the worse site with a far better one open. His own remark. No oracle.
Joke two is the oracle. Tacitus has Byzantine envoys tell the Roman Senate that when the Greeks asked Apollo at Delphi where to found their city, he said: "opposite to the blind men's country". Strabo records the same saying. Legend, told and retold.
Why the better site? Both say fish. Tacitus: fertile soil, productive seas, fish pouring in from the Black Sea. Strabo gets specific: tuna-like pelamydes shy from a white rock on Chalcedon's shore and get carried to Byzantium's side. Chalcedon gets none. Add a point that controls the way into two seas.
So the city was never "the city of the blind". The blind were the neighbours. Not fools, just first.
Take the ferry from Eminönü or Karaköy to Kadıköy: 20 to 35 minutes, depending on the boat (confirm at Şehir Hatları; fog and storms cancel). Stand at the stern and watch the "better site", Sarayburnu, recede, then look back at it from the blind men's shore. The insider move: the crowd stays on the Galata Bridge with the fishing lines; you cross and walk Kadıköy's market lanes.
