Culture of ancient Rome
The Roman Empire, at its height (c. 117 CE), was the most extensive political and social structure in western civilization. By 285 CE the empire had grown too vast to be ruled from the central government at Rome and so was divided by Emperor Diocletian into a Western and an Eastern Empire. The Roman Empire began when Augustus Caesar became the first emperor of Rome (31 BCE) and ended, in the west, when the last Roman emperor, Romulus Augustulus, was deposed by the Germanic King Odoacer (476 CE). In the east, it continued as the Byzantine Empire until the death of Constantine XI and the fall of Constantinople to the Ottoman Turks in 1453 CE. The influence of the Roman Empire on western civilization was profound in its lasting contributions to virtually every aspect of western culture.
Byzantine Empire
A nephew of the last Emperor, Constantine XI, Andreas Palaiologos claimed to have inherited the title of Byzantine Emperor. He lived in the Morea until its fall in 1460, then escaped to Rome where he lived under the protection of the Papal States for the remainder of his life. Since the office of emperor had never been technically hereditary, Andreas' claim would have been without merit under Byzantine law. However, the Empire had vanished, and Western states generally followed the Roman-church-sanctioned principles of hereditary sovereignty. Seeking a life in the west, Andreas styled himself "Imperator Constantinopolitanus" ("Emperor of Constantinople"), and sold his succession rights to both Charles VIII of France and the Catholic Monarchs.