Chalcedon (Χαλκηδών, sometimes transliterated as Chalkedon) was an ancient maritime town of Bithynia, in Asia Minor, almost directly opposite Byzantium, south of Scutari (modern Üsküdar). Today, in modern Turkish, Chalcedon is called Kadıköy and a district of Istanbul, Turkey.
40°59′N 29°02′E / 40.983°N 29.033°E