to the newly created vicars of dioceses. He funded the building of several churches and allowed clergy to act as arbitrators in civil suits (a measure that did not outlast him but which was restored in part much later). He transformed the town of Byzantium into his new residence, which, however, was not officially anything more than an imperial residence like Milan or Trier or Nicomedia until given a city prefect in May 359 by Constantius II; Constantinople. Christianity in the form of the Nicene Creed became the official religion of the empire in 380, via the Edict of Thessalonica issued in the name of three emperors – Gratian, Valentinian II, and Theodosius I – with Theodosius clearly the driving force behind it. He was the last emperor of a unified empire: after his death in 395, his sons, Arcadius and Honorius divided the empire into a western and an eastern part. The seat of government in the Western Roman Empire was transferred to Ravenna in 408, but from 450 the emperors mostly resided in the capital city, Rome. Rome, which had lost its central role in the administration of the empire, was sacked in 410 by the Visigoths led by Alaric I, but very little physical damage was done, most of which were repaired. What could not be so easily replaced were portable items such as artwork in precious metals and items for domestic use (loot). The popes embellished the city with large basilicas, such as Santa Maria Maggiore (with the collaboration of the emperors). The population of the city had fallen from 800,000 to 450–500,000 by the time the city was sacked in 455 by Genseric, king of the Vandals. The weak emperors of the fifth century could not stop the decay, leading to the deposition of Romulus Augustus on 22 August 476, which marked the end of the Western Roman Empire and, for many historians, the beginning of the Middle Ages. The decline of the city's population was caused by the loss of grain shipments from North Africa, from 440 onward, and the unwillingness of the senatorial class to maintain donations to support a population that was too large for the resources available. Even so, strenuous efforts were made to maintain the monumental centre, the palatine, and the largest baths, which continued to function until the Gothic siege of 537. The large baths of Constantine on the