Baptistery of St. John the Baptist

The Baptistery of St. John the Baptist Greek: Βαπτιστήριο Αγίου Ιωάννη του Προδρόμου) is a Greek Orthodox baptistery located in Thessaloniki, in Central Macedonia, Greece. It is considered to be the oldest early-Christian baptistery and is situated within a five-aisled episcopal basilica that was completed in the fifth century, during the Byzantine era.