Constantine, one of the greatest emperors in history, is well-known for being the first Christian Roman Emperor and issued the Edict of Milan, which announced religious toleration throughout the empire. Constantine also transformed the antique Byantium into a new prosperous residence, Constantinople, which would remain the capital of the Byzantine Empire for over a thousand years.
For political purpose, Constantine had issued the Edict of Milan so as to earn the supports from the Christian. According to the edict, Christianity became a tolerated and legal religion, therefore; the followers were no longer persecuted. The edict also returned the Church properties which were confiscated by the Roman Empire, and ruled Sunday as the day for worship. The Edict of Milan removed all obstacles to the Christian faith. From a group of followers to one of the largest religions in the world, Christianity spread and grew in a tremendous rate after the Edict of Milan was proclaimed. This edict also made the Empire officially neutral with regard to religious worship. It neither made paganism illegal nor made Christianity the state religion, but most of the edicts that Constantine had made were believe to cause great effects in the development of Christianity.
To resist the invasion from the German, Constantine moved the capital to an eastern city, Byzantium, which is easily defended. He rebuilt and extended antique Byzantium to become a brilliant region, and called Constantinople. Due to its special location, Byzantine Empire was able to make contact with wealthy eastern world and help the growth of their economy. A large among of eastern cultures were added into Roman cultures and abundant their civilization at the same time. Constantine could also protect Roman world from the aggression of eastern invaders by built up a line of defense from Constantinople.
Constantine the Great had legislated many edicts which helped the Christianity to spread out rapidly. Although the development of Constantinople he made had led to the separation of Roman, but it had also saved both Greek and Latin culture from the German. These are two of the most important contributions that Constantine had left the world.