Final answer:
Justinian the Great was the emperor of the Byzantine Empire, ruling from 527 A.D. to 565 A.D., and A.D. represents 'Anno Domini'. He is remembered for his contributions to Byzantine architecture, his endeavor to unify Christianity, and as a formidable lawgiver.
Step-by-step explanation:
Justinian the Great became emperor of the Byzantine Empire and ruled from 527 A.D. – 565 A.D. A.D. also stands for Anno Domini, which is Latin for 'in the year of our Lord', indicating the years after the birth of Jesus.
Justinian is remembered as a significant ruler for various reasons. His reign is noted for the sponsorship of enduring Byzantine architecture, the attempted enforcement of religious uniformity, and his stance as both the spiritual leader of the Christian church and the secular ruler of the empire. Moreover, he called himself "beloved of Christ," a title his successors would use. Justinian's influence stretched beyond just military and religious aspects, as he also codified Roman laws, now known as Justinian's Code.