Justinian I, orig. Petrus Sabbatius, (born 483, Tauresium, Dardania—died Nov. 14, 565, Constantinople), Byzantine emperor (527–565). Determined to regain former Roman provinces lost to barbarian invaders, Justinian conquered the Vandals in northern Africa in 534 and enjoyed an initial victory over the Ostrogoths in Italy in 540. War with the Goths, however, lasted another two decades and brought great devastation before Justinian gained control of the whole of Italy in 562 . He was unable to prevent Bulgars, Slavs, Huns, and Avars from carrying out raids along the empire’s northern frontier. He also carried on an intermittent war with Persia until 561. He reorganized the imperial government and commissioned the reform and codification of the great body of Roman law known as the Code of Justinian. His efforts to root out corruption triggered a revolt in Constantinople in 532 that nearly toppled his government; his wife, Theodora, helped him put down the revolt. Like all Roman emperors, Justinian was an active builder, and his many public works projects included the reconstruction of cities and the construction of the church of Hagia Sophia, one of the finest and most famous buildings in the world.
