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.
Council of Chalcedon
Chalcedon was a city in Bithynia, on the Asian side of the Bosphorus; today the city is part of the Republic of Turkey and is known as Kadıköy (a district of Istanbul).