Baptistery of St. John the Baptist (Thessaloniki)

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. The baptistery was identified at the excavations of the Byzantine church of Hagia Sophia. It consists of a room with platforms and includes a baptismal font. It was in direct contact with the royal in the 5th century from the hallway with a mosaic floor. The baptistery is located within the Galerian Palace complex.