He has the Edict of Milan, which makes Christianity illegal under Roman rule. Maybe most famously, on his deathbed, he gets baptized. He becomes the first Christian emperor. He also moves the capital to, officially moves the capital of the entire empire to what at the time was Byzantium, but then he renames it to Constantinople, named after him. Now it was still one unified empire. Even Diocletian, who co-ruled with a co-emperor, he had veto power over the emperor to the west. Now as we get further into the fourth century here, and especially into the fifth century, we'll see that the empire further and further fragments and gets diluted and really just breaks down.