The Angel Gabriel
Detail photograph from the right frame of the apse
Basilica of Sant'Apollinare in Classe, Ravenna, Italy
There is a corresponding image of St. Michael on the left frame of the apse. Each angel holds a military standard called a labarum, as they usually do when they flank a sacred space or personage. The most traditional labara have a chi-rho symbol at the top and something related to Constantine's adoption of Christianity on the cloth. Here, however, there is no chi-rho and to mark the sacred space beneath the apse the cloth bears the Greek words ΑΓΙΟC ΑΓΙΟC ΑΓΙΟC, "Holy Holy Holy." That phrase appears in Isaiah 6:3, Revelation 4:8, and the Sanctus, a prayer in the Roman Catholic Liturgy.
This image in full resolution
More of St. Gabriel
Photographed at the basilica by Richard Stracke, shared under Attribution-NonCommercial-ShareAlike license.