While the western half of the Roman Empire, with its capital at Rome, was invaded and overthrown by Germanic tribespeople, the eastern half of the Empire survived and thrived as a Christianised society with Constantinople as its capital. Christian Empire The most illustrious ruler of Constantinople was Justinian, who ruled 527-565. During that time, he was able, albeit temporarily, to reclaim some lands occupied by Germanic peoples (such as the Vandals in North Africa). He also engaged in a building programme – most famously reconstructing the Hagia Sophia after the Nika riot. And he is known for having codified Roman law. The two-headed eagle of Constantinople represents the "harmony" of the priesthood and the kingdom, i.e. the church and state working in tandem. In the East, unlike in the west, this always meant the state had the upper hand (this is sometimes termed "Caesaropapism") with the Emperor possessing divinely ordained power, and above the law. After Just...