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
The dogmatical disputes raised during the Council of Chalcedon led to the Chalcedonian Schism thus to the formation of the Non-Chalcedonian body of churches known as Oriental Orthodoxy. The Chalcedonian churches remained united with the Holy See of Rome, the Ecumenical Patriarchate of Constantinople (or "New Rome") and the Eastern Orthodox patriarchates of the Middle East (namely Alexandria, Antioch and Jerusalem). Together, these five patriarchates were considered the pillars of orthodox catholic Christendom and of the Chalcedonian confession of faith. During the 6th-century reign of Emperor Justinian I, the five patriarchates were recognised as the Pentarchy, the official ecclesiastical authority of the Imperial Christian Church.