What is "resafa"

Resafa ( [reṣafa]), known in Roman times as Sergiopolis (which has namesakes) and briefly as Anastasiopolis, was a city located in the Roman province of Euphratensis, in modern-day Syria. It is an archaeological site situated south-west of the city of Ar Raqqah and the Euphrates.

Procopius describes at length the ramparts and buildings erected there by Justinian. The walls of Resafa which are still well preserved are over 1600 feet in length and about 1000 feet in width; round or square towers were erected about every hundred feet; there are also ruins of a church with three apses.