The Ecclesiastical History Of Scholasticus by Socrates Scholasticus
Chapter XVI.--The Emperor Constantine having enlarged the Ancient Byzantium, calls it Constantinople.
After the Synod the emperor spent some time in recreation, and after the public celebration of his twentieth anniversary of his accession, he immediately devoted himself to the reparation of the churches. This he carried into effect in other cities as well as in the city named after him, which being previously called Byzantium, he enlarged, surrounded with massive walls, and adorned with various edifices; and having rendered it equal to imperial Rome, he named it Constantinople, establishing by law that it should be designated New Rome. This law was engraven on a pillar of stone erected in public view in the Strategium, near the emperor's equestrian statue. He built also in the same city two churches, one of which he named Irene, and the other The Apostles. Nor did he only improve the affairs of the Christians, as I have said, but he also destroyed the superstition of the heathens; for he brought forth their images into public view to ornament the city of Constantinople, and set up the Delphic tripods publicly in the Hippodrome. It may indeed seem now superfluous to mention these things, since they are seen before they are heard of. But at that time the Christian cause received its greatest augmentation; for Divine Providence preserved very many other things during the times of the emperor Constantine. Eusebius Pamphilus has in magnificent terms recorded the praises of the emperor; and I considered it would not be ill-timed to advert thus to them as concisely as possible.