The Baptistery of St. John the Baptist of Thessaloniki, considered as the oldest early Christian baptistery and assigned to the building complex of a five-aisled episcopal basilica of the fifth century.
[1] The baptistery was identified at the excavations of the Byzantine church of Hagia Sophia.
It consists of a room with platforms and includes a font.
It was in direct contact with the royal in the 5th century from the hallway with a mosaic floor.
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