The Byzantine Rite, sometimes called the Rite of Constantinople or Constantinopolitan Rite, is the liturgical rite used currently (in various languages) by all the Eastern Orthodox Churches and by the Greek-Catholic Churches (Eastern Catholic Churches which use the Byzantine Rite). The rite developed in the city of Constantinople (now Istanbul), which had earlier been called Byzantium. It is the second largest liturgical rite in Christendom, second in world-wide usage only to the Roman Rite.