I recently read the two-volume novel, The Sarantine Mosiac, on the advice of Joquandor (many thanks, and your new site design is quite lovely and easy on the eyes :-). I had attempted to read an early book by Guy Favriel Kay and found it unreadable. However, these two books, Sailing to Sarantium and Lord of Emperors were wonderful. They are catagorized as fantasy novels, but Kay has based his time, place and characters on the historical Byzantine Empire. It is so close to the actual Byzantium that the books read more like historical novels than fantasy. In fact, the fantasy element is mininimal. The magic comes from the "old gods" struggling for their existence as they are edged out by the belief in the one true God. If you have any interest in Byzantium or Early Christian Rome, read these books.
That being said, I just wanted to talk about the main chracter, Crispin the mosaicist, and his mosaics. Cripsin is called to Sarantium (sort of) to decorate the huge new dome being built by the Emperor Valerius II. One cannot sail to Sarantium without being changed, and Crispin is no exception. He is thrown head first into a maze of court intrigues - not as byzantine as in some stories I've read - but complicated enough. Crispin keeps trying to tell everyone that he is merely an artisan, as if one's vocation matters when a pawn is needed. He comes to know personally all the major players in a time of major upheavals.
Kay obviously did some extensive research on the Byzantine Empire as well as the art of mosaics. The most beautiful and most stunning mosaics still in situ are from this time period. Anyone who remembers Art 101 will remember the mosaics at Ravenna.

The image above is the Empress Theodora and her retinue. A very good basic paper on her can be found here. The Empress Alixana in Kay's books is not so loosely based on Theodora.

This is the Emperor Justinian. Both of these mosaics are on the walls of St. Apollinare in Ravenna, Italy, done in the late 6th century. You can see more of the mosaics here
Without giving anything away, let's just say that these images will play a major role in the books. However, as I read his descriptions of the mosaics, I realized he was not talking about early Christian art, but rather late Roman. Early Christian art, as seen above, is very stiff and formal, and not as concerned with rendering images realistically as with representing an idea in icon form. Roman art, on the other hand, was more about the real world and the things and people around us.
I found a great site for examples of Roman mosaics, but the images are BBC copywrited, so just go there and click on the first three images on the list at the top of the page and marvel at the beauty of these images. Where Byzantine mosaics are grand and stately, calculated to overwhelm the viewer with their awesome power and glittering surface, the Roman mosaics are fine paintings, delicately created to capture the essence of the person or thing.
In Sailing to Sarantium, Kay describes Crispin's design for the new dome as a huge landscape showing land and sea and Sarantium itself, as well as an image of the god. There is an amount of detail that just does not appear in early Christian works of any kind. Crispin's mosaic is more of a mixture of the two arts.
Anyway, it's a very good read, and now you have some background for the images. It kind of gives the story an even richer texture when you have these images in your mind. Happy reading!