The second event of primary importance during Constantine’s reign, next to the recognition of Christianity, was the foundation of a new capital on the European shore of the Bosphorus, at its entrance to the Propontis (Sea of Marmora), on the site of the former Megarian colony, Byzantium (Βυζαντιον).
Long before Constantine the ancients had been fully aware of the strategic and commercial advantages of Byzantium, situated as it was on the border of Asia and Europe, commanding the entrance to two seas, the Black and the Mediterranean. It was also close to the main sources of the glorious ancient cultures. Judging by the sources, in the first half of the seventh century B.C. the Megarians had founded a colony named Chalcedon, on the Asiatic shore of the southern end of the Bosphorus, opposite the site where Constantinople was built in later years. A few years after the founding of this colony another party of Megarians established a colony on the European shore of the south end of the Bosphorus, Byzantium, named for the chief of the Megarian expedition, Byzas (Βυζας). The advantages of Byzantium over Chalcedon were well understood by the ancients. The Greek historian of the fifth century, B.C., Herodotus (iv, 144) wrote that the Persian general, Megabazus, upon arriving at Byzantium, called the inhabitants of Chalcedon blind people, because, having a choice of sites for their city, they had chosen the worse of the two, disregarding the better site, where Byzantium was founded within a few years. Later literary tradition, including Strabo (vii, 6, c. 320) and the Roman historian, Tacitus (Ann. xii, 63), ascribes this statement of Megabazus, in a slightly modified form, to the Pythian Apollo who, in answer to the Megarian’s question as to where they should build the city, answered that they should settle opposite the land of the blind. Byzantium played an important part during the epoch of the Greco-Persian Wars and the time of Philip of Macedon. The Greek historian of the second century B.C., Polybius, analyzed thoroughly the political and economic position of Byzantium. Recognizing the importance of trade relations between Greece and the cities along the Black Sea, he wrote that without the consent of the inhabitants of Byzantium not a single commercial vessel could enter or leave the Black Sea and that the Byzantians thus controlled all the indispensable products of the Pontus.
After Rome ceased to be a republic the emperors more than once wanted to transfer the capital from republican-minded Rome to the East. According to the Roman historian, Suetonius (I, 79), Julius Caesar intended to move from Rome to Alexandria or to Ilion (former Troy). In the first centuries of the Christian era the emperors often deserted Rome for long periods during their extensive military campaigns and journeys through the empire. At the end of the second century Byzantium received a heavy blow: Septimius Severus, upon defeating his rival, Pescennius Niger, who was supported by Byzantium, submitted the city to a terrible sack and almost complete destruction. Meanwhile the East continued to attract the emperors. Diocletian (284-305) preferred to live in Asia Minor in the Bithynian city, Nicomedia, which he beautified with many magnificent new edifices.
When Constantine decided to create a new capital, he did not choose Byzantium at once. For a while, at least, he considered Naissus (Nish) where he was born, Sardica (Sofia), and Thessalonica. His attention turned particularly to Troy, the city of Aeneas, who according to tradition, had come to Latium in Italy and laid the foundations for the Roman state. The Emperor set out personally to the famous place, where he himself defined the limits of the future city. The gates had already been constructed when, as Sozomen, the Christian writer of the fifth century, related, one night God visited Constantine in a dream and induced him to look for a different site for his capital. After this Constantine’s choice fell definitely upon Byzantium. Even a century later travelers sailing near the shores of Troy could see the unfinished structures begun by Constantine.
Byzantium, which had not yet fully recovered from the severe destruction caused by Septimius Severus, was at that time a mere village and occupied only part of the cape extending to the Sea of Marmora. In 324 A.D. Constantine decided upon the foundation of the new capital and in 325 the construction of the main buildings was begun. Christian legend tells that the Emperor, with spear in his hand, was outlining the boundaries of the city when his courtiers, astonished by the wide dimensions planned for the capital, asked him, “How long, our Lord, will you keep going?” He answered, “I shall keep on until he who walks ahead of me will stop.” This was meant to indicate that some divine power was leading him. Laborers and materials for the construction work were gathered from everywhere. Pagan monuments of Rome, Athens, Alexandria, Ephesus, and Antioch were used in beautifying the new capital. Forty thousand Goth soldiers, the so-called “foederati,” participated in the construction of the new buildings. Many commercial and financial privileges were proclaimed for the new capital in order to attract a larger population. Toward the spring of 330 A.D. the work had progressed to such an extent that Constantine found it possible to dedicate the new capital officially. The dedication took place on May 11, 330 and was followed by celebrations and festivities which lasted for forty days. In this year Christian Constantinople was superimposed upon pagan Byzantium.
Although it is difficult to estimate the size of the city in the time of Constantine, it is certain that it exceeded by far the extent of the former Byzantium. There are no precise figures for the population of Constantinople in the fourth century; a mere assumption is that it might have been more than 200,000. For protection against the enemy from the land, Constantine built a wall extending from the Golden Horn to the Sea of Marmora.
In later years ancient Byzantium became the capital of a world empire and it was called the “City of Constantine” or Constantinople. The capital adopted the municipal system of Rome and was subdivided into fourteen districts or regions, two of which were outside the city walls. Of the monuments of Constantine’s time almost none have survived to the present day. However, the Church of St. Irene, which was rebuilt twice during the time of Justinian the Great and Leo III, dates back to Constantine’s time and is still preserved. The famous small serpent column from Delphi (fifth century B.C), erected in commemoration of the battle of Plataea, transferred by Constantine to the new capital, and placed by him in the Hippodrome, is still there today, although it is somewhat damaged.
Constantine, with the insight of genius, appraised all the advantages of the position of the city, political as well as economic and cultural. Politically, Constantinople, or, as it was often called, the “New Rome,” had exceptional advantages for resisting external enemies. It was inaccessible from the sea; on land it was protected by walls. Economically, Constantinople controlled the entire trade of the Black Sea with the Aegean and the Mediterranean seas and was thus destined to become the commercial intermediary between Europe and Asia. Finally, in the matter of culture, Constantinople had the great advantage of being situated close to the most important centers of Hellenistic culture, which under Christian influence resulted in a new Christian-Greco-Roman, or “Byzantine,” culture. Th. I. Uspensky wrote:
The choice of a site for the new capital, the construction of Constantinople, and the creation of a universal historical city is one of the indefeasible achievements of the political and administrative genius of Constantine. Not in the edict of religious toleration lies Constantine’s great service to the world: if not he, then his immediate successors would have been forced to grant to Christianity its victorious position, and the delay would have done no harm to Christianity. But by his timely transfer of the world-capital to Constantinople he saved the ancient culture and created a favorable setting for the spread of Christianity.
Following the period of Constantine the Great, Constantinople became the political, religious, economic, and cultural center of the Empire.