What are the unique features of Byzantine art and architecture?

Although Byzantine art evolved from the traditions of the
Roman Empire and never totally lost sight of its classical heritage, Byzantine painting
and architecture tended to shy away from Rome's realistic roots, instead developing its
own abstract forms that were more anti-naturalistic. Byzantine art took on a symbolic
aesthetic that was at least somewhat influenced by the Orient. Religious and imperial
themes predominated, and the image of Christ became a major figure in both art and
sculpture. In addition to church architecture, religious frescoes, mosaics, decorative
silks and the illumination of manuscripts were also important genres. Byzantine
architecture also developed from traditional Roman styles, combining Eastern and even
Greek influences while adding a geometric complexity not found in earlier forms. Brick
and plaster were added to the classic stone structures, and piers and domes were also
important elements.