Final answer:
Byzantine churches placed decorative mosaics on ceilings to convey important religious messages to the congregation, serving as both an artistic and didactic tool. These expensive and elaborate artworks adorned the interiors of prominent churches such as Hagia Sophia and demonstrated the wealth and devotion of elite patrons.
Step-by-step explanation:
The ceilings of Byzantine churches were adorned with mosaics, a form of art involving the assembly of small pieces of colored glass, stone, or precious tiles called tesserae. Unlike the Romans who placed mosaics on the floors, the Byzantines considered Christian-themed mosaics too sacred to be walked upon and instead placed them on the ceilings of churches. Such decorative mosaics served a dual purpose - they were not only a demonstration of the wealth and devotion of elite donors, such as emperors, but also functioned to convey important religious messages to the congregation.
Facilities like the iconic Hagia Sophia, the cathedral in Constantinople, now Istanbul, and the church of San Vitale in Ravenna are prime examples of this ornate style. In these churches, mosaics depicted holy figures and were part of an iconographic scheme meant to inspire and educate those who viewed them. Given the complexity and expense involved in creating mosaics, they were often funded by imperial or other affluent benefactors who wished to demonstrate their piety and support for the church.
Byzantine mosaics were vast and took much patience and skill to create, with some taking over twenty years to complete. The Hagia Sophia itself is renowned for its walls and domes covered with intricate mosaics that once illustrated Christian writings and themes, which were later covered or removed during its conversion to a mosque.