Constantine
Specifically, Constantine I, the 57th Emperor of the Roman Empire. He moved the capital to Byzantium, and renamed the city to Constantinople (now Istanbul). He was also the first Christian emperor.
Constantine! I just learned about this in my World History class two weeks ago!
The Roman leader you are referring to is Constantine. He was the first emperor to accept Christianity and moved the capital from Rome to Byzantium, renaming it Constantinople in 330 C.E. His reign marked a significant turning point for Christianity in the Roman Empire.
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