This slab has been scanned at the Archiepiscopal Museum Museum in Ravenna located next to the Bapistry of Neon and behind the Duomo of Ravenna.
In the museum relics of early Christian Ravenna are preserved, including fragments of mosaic from the first cathedral church, and the chapel of Sant'Andrea, dating from the Gothic kingdom.
The museum houses the private chapel of the bishop, built in the time of Theodoric (end of the 5th century) and dedicated to Sant'Andrea (Saint Andrew). A central feature is the little contemplation of the Word, encapsulated in the initials of Christ, and which reaffirms the Orthodox creed reigning, when the Arians had supremacy in Ravenna: The vault of the narthex, as you enter, is an exquisite working of blues and greens in which all the aquatic birdlife of Ravenna is interlaced; the lower parts have been restored cleverly with painted 'mosaic', including the inscription: Aut lux hic nata est, aut capta hic libera regnat ("Either light was born here or it was captured, [either way, here it] reigns freely") - which, apart from being a very fine appreciation of the art of mosaic, might be a cunning allusion to the 'Babylonian Captivity' of the Light, ('begotten not made') in the years of the Gothic occupation.
Above the door is a lunette decorated with a young warrior Christ - the proud Roman soldier and not the Man of Sorrows, shouldering his cross, displaying the book which says I am the Way, the Truth and the Life; the lion and the snake he treads under foot are taken as the forces of evil (here, Arianism) which he defeats. Unfortunately, the chapel itself was heavily repainted with Renaissance frescoes (by Luca Longhi, a local artist) and marbling to give the same intimate feeling as the narthex. The apse has a starry sky which may have been inspired by the oratory of Galla Placidia; the vaulting has four angels arching inward to sustain the symbol of Christ: the initials I X = IesusXristos; between them, the symbols of the Evangelists and, in the vault of apse, portraits of the first Apostles Ss. Peter and Paul, James and Philip, Andrew and Jacob, with Christ, intent upon the Word and its interpretation. Even more than in the Christology of Galla Placidia, the Son of God is seen in the vault of Heaven: the Logos of the Cosmos. Robbed of earthly dominion, under Theodoric, the bishops of Ravenna contemplated celestial glory.
The chapel is included in the series of monuments of Ravenna classed by UNESCO as a world heritage site.
(Text credit to Wikipedia)