It would be hard if not outright impossible to overstate the impact Roman Emperor Constantine I had on the history of Christianity, Ancient Rome, and Europe as a whole. Best known as Constantine the Great, the kind of moniker only earned by rulers who have distinguished themselves in battle and conquest, Constantine remains an influential and controversial figure to this day. He achieved enduring fame by being the first Roman emperor to personally convert to Christianity, and for his notorious Edict of Milan, the imperial decree which legalized the worship of Christ and promoted religious freedom throughout the empire. More than 1500 years after Constantine’s death, Abdu'l-Bahá, the head of the Bahá'í Faith, wrote, “His blessed name shines out across the dawn of history like the morning star, and his rank and fame among the world's noblest and most highly civilized is still on the tongues of Christians of all denominations.”

Moreover, even though he is best remembered for his religious reforms and what his (mostly Christian) admirers described as his spiritual enlightenment, Constantine was also an able and effective ruler in his own right. Rising to power in a period of decline and confusion for the Roman Empire, he gave it a new and unexpected lease on life by repelling the repeated invasions of the Germanic tribes on the northern and eastern borders of the Roman domains, even going so far as to re-expand the frontier into parts of Trajan’s old conquest of Dacia (modern Romania), which had been abandoned as strategically untenable.

Due to the importance of the Roman Empire and the offshoot Byzantine Empire, it’s often forgotten that Constantinople wasn’t chosen at random; in fact, the city already existed, and it lent its name to the empire that was subsequently centered there. Byzantium, known originally as Byzantion, was an ancient Greek city centuries before it became known as Constantinople.