This lecture looks at the main characteristics of the art of the Orthodox Church from the time when Constantinople was established as the capital of the Eastern Roman – and Christian – Empire in the 4th century AD until its fall to the Ottoman Turks in 1453, and beyond. It concentrates on the areas and countries which became part of what has been described as the Byzantine Commonwealth, including Ravenna, Greece, Bulgaria and Romania, as well as Constantinople itself, the source and model for the Orthodox Church everywhere. But the main emphasis will be on the architecture of some selected churches, icons and frescoes, to explain the spiritual and religious messages and meanings that they convey.