Chalcedon
The site of Chalcedon is located on a small peninsula on the north coast of the Sea of Marmara, near the mouth of the Bosphorus. A stream, called the Chalcis or Chalcedon in antiquity and now known as the Kurbağalıdere (Turkish: "stream with frogs"), flows into Fenerbahçe bay. There Greek colonists from Megara in Attica founded the settlement of Chalcedon in 685 BC, some seventeen years before Byzantium.
Byzas
When Byzas arrived to where the Sea of Marmaras meets the Sea of Bosporos, on the border of Europe and Asia, he realized the meaning of the oracle. On the Asian shore, opposite to where he was, a colony, Chalcedon, had already been established. Byzas decided that Chalcedon was the prophesied 'city of the blind', as it had not taken advantage of the European shore.