The Triumphal Arch at San Vitale

Left side
Right side

6th century
Basilica of San Vitale, Ravenna

Left side in full resolution
Right side in full resolution

Also see close-ups of the medallions for Saints Gervasius, Protasius, Peter, Paul, and Andrew.

Photographed at the basilica by Richard Stracke, shared under Attribution-NonCommercial-ShareAlike license.