Constantius II in the context of "Byzantine Senate"

The Church of Cyprus (Greek: Ἐκκλησία τῆς Κύπρου, romanized: Ekklisia tis Kyprou) is one of the autocephalous Greek Orthodox churches that form part of the communion of the Eastern Orthodox Church. Based in Cyprus, it is one of the oldest Eastern Orthodox autocephalous churches; it claims to have always been independent, although it may have been subject to the Church of Antioch before its autocephaly was recognized in 431 at the Council of Ephesus. The bishop of the ancient capital, Salamis (renamed Constantia by Emperor Constantius II) was constituted metropolitan by Emperor Zeno, with the title archbishop.

The Imperial Library of Constantinople, in the capital city of the Byzantine Empire, was the last of the great libraries of the ancient world. Long after the destruction of the Great Library of Alexandria and the other ancient libraries, it preserved the knowledge of the ancient Greeks and Romans for almost 1,000 years. A series of unintentional fires over the years and wartime damage, including the raids of the Fourth Crusade in 1204, impacted the building and its contents. While there were many reports of texts surviving into the Ottoman era, no substantive portion of the library has ever been recovered. The library was founded by Constantius II (reigned 337–361 AD), who established a scriptorium so that the surviving works of Greek literature could be copied for preservation. The Emperor Valens in 372 employed four Greek and three Latin scribes. The majority of Greek classics known today are known through Byzantine copies originating from the Imperial Library of Constantinople.

Julian (Latin: Flavius Claudius Julianus; Ancient Greek: Ἰουλιανός Ioulianos; 331 – 26 June 363) was the Caesar of the West from 355 to 360 and Roman emperor from 361 to 363, as well as a notable philosopher and author in Greek. His rejection of Christianity, and his promotion of Neoplatonic Hellenism and persecution of Christians, caused him to be remembered as Julian the Apostate in the Christian tradition.

A nephew of Constantine the Great, Julian was one of few in the imperial family to survive the purges and civil wars during the reign of Constantius II, his cousin. Julian became an orphan as a child after his father was executed in 337, and spent much of his life under Constantius's close supervision. However, the emperor allowed Julian freedom to pursue an education in the Greek-speaking east. In 355, Constantius II summoned Julian to court and appointed him to rule Gaul. Julian was successful in his rule, defeating and counterattacking Germanic raids across the Rhine and encouraging the provinces' return to prosperity. In 360, he was proclaimed emperor by his soldiers at Lutetia (Paris), sparking a civil war with Constantius. However, Constantius died before the two could face each other in battle, having named Julian as his successor to prevent further bloodshed.

Constantine II (Latin: Flavius Claudius Constantinus; 316–340) was Roman emperor from 337 to 340. The son of the emperor Constantine I, he was proclaimed caesar by his father shortly after his birth. He was associated with military victories over the Sarmatians, Alamanni and Goths during his career, for which he was granted a number of victory titles. He held the consulship four times – in 320, 321, 324, and 329.

Constantine I had arranged for his sons to share power with their cousins Dalmatius and Hannibalianus, but this was not accepted by Constantine II and his brothers. As a result, Constantine II's brother Constantius II ordered the killings of numerous male relatives following Constantine I's death, including Dalmatius and Hannibalianus, thus eliminating any possible opponents to the succession of Constantine I's sons. Constantine II then ascended to the throne alongside his two younger brothers, ruling Gaul, Hispania, and Britain. However, his belief in his rights of primogeniture and attempts to exert them over his youngest brother Constans caused conflict, which ended with his death in a failed invasion of Italy in 340. Constans subsequently took control of Constantine's territories, with the latter being subjected to damnatio memoriae.

Persecution of pagans in the late Roman Empire began during the reign of Constantine the Great (r. 306–337) in the military colony of Aelia Capitolina (Jerusalem), when he destroyed a pagan temple for the purpose of constructing a Christian church. Rome had periodically confiscated church properties, and Constantine was vigorous in reclaiming them whenever these issues were brought to his attention. Christian historians alleged that Hadrian (2nd century) had constructed a temple to Venus on the site of the crucifixion of Jesus on Golgotha hill in order to suppress Christian veneration there. Constantine used that to justify the temple's destruction, saying he was simply reclaiming the property. Using the vocabulary of reclamation, Constantine acquired several more sites of Christian significance in the Holy Land.

From 313, with the exception of the brief reign of Julian, non-Christians were subject to a variety of hostile and discriminatory imperial laws aimed at suppressing sacrifice and magic and closing any temples that continued their use. The majority of these laws were local, though some were thought to be valid across the whole empire, with some threatening the death penalty, but not resulting in action. None seem to have been effectively applied empire-wide. For example, in 341, Constantine's son Constantius II enacted legislation forbidding pagan sacrifices in Roman Italy. In 356, he issued two more laws forbidding sacrifice and the worship of images, making them capital crimes, as well as ordering the closing of all temples. There is no evidence of the death penalty being carried out for illegal sacrifices before Tiberius Constantine (r. 578–582), and most temples remained open into the reign of Justinian I (r. 527–565). Pagan teachers (who included philosophers) were banned and their license, parrhesia, to instruct others was withdrawn. Parrhesia had been used for a thousand years to denote "freedom of speech." Despite official threats, sporadic mob violence, and confiscations of temple treasures, paganism remained widespread into the early fifth century, continuing in parts of the empire into the seventh century, and into the ninth century in Greece. During the reigns of Gratian, Valentinian II and Theodosius I anti-pagan policies and their penalties increased.

Flavius Julius Constans (c. 323 – 350), also called Constans I, was Roman emperor from 337 to 350. He held the imperial rank of caesar from 333, and was the youngest son of Constantine the Great.

After his father's death, he was made augustus alongside his brothers in September 337. Constans was given the administration of the praetorian prefectures of Italy, Illyricum, and Africa. He defeated the Sarmatians in a campaign shortly afterwards. Quarrels over the sharing of power led to a civil war with his eldest brother and co-emperor Constantine II, who invaded Italy in 340 and was killed in battle by Constans's forces near Aquileia. Constans gained from him the praetorian prefecture of Gaul. Thereafter there were tensions with his remaining brother and co-augustus Constantius II (r. 337–361), including over the exiled bishop Athanasius of Alexandria, who in turn eulogized Constans as "the most pious Augustus... of blessed and everlasting memory." In the following years he campaigned against the Franks, and in 343 he visited Roman Britain, the last legitimate emperor to do so until Manuel II in 1400, more than a thousand years later.

Vetranio (died c. 356 AD) was briefly an imperial usurper and emperor in the Roman Empire in 350, during which time he controlled Illyricum between the rival emperors Magnus Magnentius and Constantius II, eventually capitulating to the latter.