Basilica of San Vitale
Byzantine architecture often featured marble columns, coffered ceilings and sumptuous decoration, including the extensive use of mosaics with golden backgrounds. The building material used by Byzantine architects was no longer marble, which was very appreciated by the Ancient Greeks. They used mostly stone and brick, and also thin alabaster sheets for windows. Mosaics were used to cover brick walls, and any other surface where fresco wouldn't resist. Good examples of mosaics from the proto-Byzantine era are in Hagios Demetrios in Thessaloniki (Greece), the Basilica of Sant'Apollinare Nuovo and the Basilica of San Vitale, both in Ravenna (Italy), and Hagia Sophia in Istanbul.