The Neonian Baptistery is one of the most ancient monuments of the city of Ravenna. It was commissioned by Bishop Urso and probably built at the beginning of the 5th century like the nearby cathedral. During the episcopacy of Neon (450 - 475), the baptistery underwent many restoration works that ended with the reconstruction of the cupola and the realization of the interior decoration, still present today. At the centre of the dome, a big medallion frames the Baptism of Christ, depicted as a young man immersed in the hips in the sheer waters of the river Jordan. This is one of the oldest mosaic scenes of the Baptism of Christ housed inside a monumental building. The images of the twelve Apostles, divided into two groups led by Saint Peter and Paul, revolve around the central medallion, standing out against a blue background. A second ring shows eight exedrae that cover thrones and altars and symbolize the concept of the heavenly city and the spread of the Christian doctrine.