Ravenna in the Roman Empire

  https://smarthistory.org/santapollinare-in-classe-ravenna-italy/ What was the function of Ravenna in the Roman Empire? Who is Saint Apollinare? Who are the four figures surrounding God on the triumphal arch? Which two cities are depicted in the mosaic? What do the two letters on either side of the cross symbolize? What is the Transfiguration? What do the six sheep on either side (twelve total) of Saint Apollinare symbolize?