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.
Chalcedonian Christianity
Chalcedonian Christianity refers to the Christian denominations adhering to the christological definitions and ecclesiological resolutions of the Council of Chalcedon, the Fourth Ecumenical Council held in 451. Chalcedonian Christians follow the Definition of Chalcedon, a religious doctrine concerning the divine and human natures of Jesus Christ. The great majority of Christian communions and confessions in the 21st century are Chalcedonian, but from the 5th to the 8th centuries the ascendancy of Chalcedonian Christology (detailed below) was not always certain.