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.
Non-Chalcedonianism
Non-Chalcedonianism is a religious doctrine of those Christian churches that do not accept the Confession of Chalcedon as defined at the ecumenical Council of Chalcedon in 451. The doctrine contrasts with Chalcedonian Christianity, which accepts the doctrines of the first seven Ecumenical Councils. Some Christian denominations do not accept the Confession of Chalcedon, for varying reasons, but accept the doctrines of the previous council at the Council of Ephesus in 431.