Source: Weitzmann, Age of Spirituality

The Transfiguration

6th century
Mosaic
Apse of the basilica of Sant' Apollinare in Classe, Italy

The cross represents the transfigured Christ.  To its right
and left are Moses and Elijah, respectively.  The figure below with the sheep is St. Apollinaris.

This image is discussed in Margaret E. Frazier's "The Christian Realm: Apse Themes,” in Weitzmann.

More of St. Apollinaris