Ravenna: Arian Baptistry - Dome Mosaic

This picture shows a detail of the mosaic of Christ's baptism. The jewelled cross, with its purple drapery, is what is known as the trophy-cross and it is probable that this is what the poet of The Dream of the Rood had in mind when he described the cross of his vision as honoured with hangings.
Sixth century.

Photograph: Archeology Institute Photo Archive, Oxford University