The memory of emperor Constantine has survived the ages as one of greatness and inspired forethought. In effect he lived in an age when the Empire’s fortunes were declining due to a variety of reasons, amongst which were chronic political instability and overstretched resources. Even the empire itself was far to large to be managed from a single location.
Constantine was able enough to shift the capital of the empire eastwards to Constantinople (now Istanbul) which in itself cannot have been an easy task. He also had the audacity to legalise Christianity: a monotheistic religion which hitherto had been in direct conflict with the very concept of paying any sort of tribute to the (Roman) Emperor-deity.
These two actions had far reaching repercussions and in many ways have directly influenced the way the western world has been shaped.
Further in-depth information about Emperor Constantine may be found here.