Chalcedon

Chalcedon is an ancient city on the Asian shore of the Bosphorus at the site of present-day Kadıköy in Istanbul. It was established by Greek colonists in the 7th century BC and became a significant settlement through classical and late antique periods.

Highlights in the area are the archaeological remains and the shoreline setting opposite ancient Byzantium, offering views across the strait to the historic peninsula. The location is notable for its continuity of settlement into the modern district of Kadıköy with layers of Greek, Roman and Byzantine heritage visible in place names and ruins.

Chalcedon was developed by Greek settlers from Megara and later came under Roman and Byzantine administration, serving as a regional centre and ecclesiastical seat. Its prominence peaked in late antiquity, notably hosting the Council of Chalcedon in 451 AD, which shaped Christian theology.

The site lies on the southern entrance to the Bosphorus on the Asian side of Istanbul, now absorbed into the urban fabric of Kadıköy and a short ferry or road crossing from the historic peninsula of Istanbul.

• Foundation: Founded by Greek colonists from Megara around the 7th century BC and later became an important Byzantine and Roman-era locality.
• Historic council: Site of the Council of Chalcedon in 451 AD, a major event in early Christian history.