The Dome of the Mausoleum of Galla Placidia
Christ and the evangelists are represented by the cross and the four winged creatures.
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View detail photographs of the eagle, the angel, the ox, and the lion.
Read more about the cross symbol and about images of the Evangelists.
Photographed at the site by Richard Stracke, shared under Attribution-NonCommercial-ShareAlike license.