The Ecclesiastical History of Sozomen

The emperor had already divided the empire among his sons, who were styled Cæsars. To Constantine and Constans he awarded the western regions; and to Constantius, the eastern; and as he was indisposed, and required to have recourse to bathing, he repaired for that purpose to Helenopolis, a city of Bithynia. His malady, however, increased, and he went to Nicomedia, and was initiated into holy baptism in one of the suburbs of that city. After the ceremony he was filled with joy, and returned thanks to God. He then confirmed the division of the empire among his sons, according to his former allotment, and bestowed certain privileges on old Rome and on the city named after himself. He placed his testament in the hands of the presbyter who constantly extolled Arius, and who had been recommended to him as a man of virtuous life by his sister Constantia in her last moments, and commanded him with an added oath to deliver it to Constantius on his return, for neither Constantius nor the other Cæsars were with their dying father. After making these arrangements, Constantine survived but a few days; he died in the sixty-fifth year of his age, and the thirty-first of his reign. He was a powerful protector of the Christian religion, and was the first of the emperors who began to be zealous for the Church, and to bestow upon her high benefactions. He was more successful than any other sovereign in all his undertakings; for he formed no design, I am convinced, without God. He was victorious in his wars against the Goths and Sarmatians, and, indeed, in all his military enterprises; and he changed the form of government according to his own mind with so much ease, that he created another senate and another imperial city, to which he gave his own name. He assailed the pagan religion, and in a little while subverted it, although it had prevailed for ages among the princes and the people.

After the death of Constantine, his body was placed in a golden coffin, conveyed to Constantinople, and deposited on a certain platform in the palace; the same honor and ceremonial were observed, by those who were in the palace, as were accorded to him while living. On hearing of his father’s death, Constantius, who was then in the East, hastened to Constantinople, and interred the royal remains with the utmost magnificence, and deposited them in the tomb which had been constructed by order of the deceased in the Church of the Apostles. From this period it became the custom to deposit the remains of subsequent Christian emperors in the same place of interment; and here bishops, likewise, were buried, for the hierarchical dignity is not only equal in honor to imperial power, but, in sacred places, even takes the ascendancy.