By Kenneth W. Harl, Ph.D., Tulane University
The Christian emperor Constantine was ever pragmatic; he could only push his pagan subjects so far. One act of his, in the end, ensured the position of Christianity: the establishment of a new capital that would be known as Constantinople.

Four Emperors, Four Capitals
By the time of Diocletian in the late 3rd century, it was already clear that Rome no longer occupied the position of the capital of the Roman Empire. During the period known as the tetrarchy, when four emperors ruled, none of them used Rome as their capital. Constantine’s father and Constantine himself ruled in Germany, on the Rhine frontier. The senior emperor in the West usually resided in Milan, in northern Italy. The senior emperor in the East was usually somewhere in Turkey; Diocletian’s capital was at Nicomedia. The junior emperor generally lived at Antioch in Syria. Major cities were chosen that were closer to frontiers and closer to the resources necessary to battle barbarians and suppress rebels.

Learn more about a conservative emperor named Diocletian
A New Rome in Byzantium
Rome increasingly became a ceremonial capital. It was awkwardly placed. To this day, Rome really isn’t the capital of Italy, at least not in a financial or economic sense. Its importance is due to its political and religious significance. However, there was always a move to get the capital out of Rome to a better location.
This is a transcript from the video series The World of Byzantium. Watch it now, on The Great Courses.
Constantine, therefore, in many ways, was responding along the lines of what other soldier-emperors had done. Constantine made a major difference here. He decided to establish a capital, “New Rome,” which would be Christian in nature from the start. There would be no pagan gods. He chose the city of Byzantium, where we get the word “Byzantine”—Byzantine civilization.
Byzantium was an old Greek colony, established in the 7th century B.C. It occupies the European side of the Bosporus, the narrow strait that leads from the Sea of Marmara, which in ancient times they called the Propontis, into the Black Sea. It was a very important commercial center. As a city, it had never been more than 30,000 to 35,000 strong. Under Constantine, the city was vastly expanded. It eventually came to number perhaps a half-million—some would say a million—by A.D. 500.

It would be surrounded by a series of walls, some 13 miles in length, and was completely made over as the equivalent of the New Rome. A whole palace complex was constructed. There was an imperial Hippodrome or stadium where all the imperial races and ceremonials took place. The city was to represent Rome in every fashion, except for the detail that it was to be Christian.
Therefore, at the New Rome, there was a Senate house. Constantine handed out pensions, tax exemptions, and encouraged men to come and serve in the new Christian imperial Senate, whereas the old Roman pagan Senate Constantine could conveniently ignore.
Learn more: The Good Life in Rome
Building an Urban Mob
At the same time, Rome had an urban population that was necessary to feed and pamper at great festivals, chariot races, gladiator combats. As a Christian emperor, gladiatorial combat was wrong but chariot races were acceptable. These ceremonies had to continue, and to be effective, you had to have an audience. Constantine was insistent in ensuring that his new capital would have, in effect, an urban mob.
One wonders how people were contracted to try out for this position. Nonetheless, a mob was created, urban plebian, that would act as the ceremonial elite that would be privileged, that would be given the free bread and circuses that you would have in Old Rome. Many of the features of Old Rome were reproduced in Constantinople—for instance, Seven Hills. Constantine went around naming seven hills to represent the Seven Hills of Rome, although he had to fake on one of them.
Learn more about what alternatives poor Romans had
Christianity—The Faith that Mattered

All of this was extremely important in stressing the continuity of the ancient Roman past. At the same time, it marked a major change. In A.D. 330, the city was dedicated as an imperial city. Imperial churches emerged that became the model for constructing churches in provincial cities. The Roman Senate in Constantinople was encouraged to be Christian and the court was Christian in tone. It gave its authority, its seal, behind the new faith.
This was the faith that would matter. If you wished to rise in society, it was best to go to Constantinople. It was best to become a Christian. It was best to work your way through the imperial government. Old Rome, the Senate of Rome, the pagans that still populated much of the provincial area, were increasingly taking second place.
Learn more about transforming Christianity from a minority, illegal religion to the majority, official religion of the Empire
The cultural and political reins were now firmly in the hands of the Christian imperial family. They would favor their coreligionists. That was the decisive act that made it possible to turn the Roman Empire, eventually, into a Christian empire.
An Economic and Political Center
Between A.D. 324 and A.D. 400, the population increased by at least tenfold.
Constantinople had several roles to play, more than just being the capital. It’s difficult for us to understand, in some ways, the vast importance of Constantinople. It was known as the “Queen of Cities” through much of the Middle Ages. Between A.D. 324—when the city was still Byzantium and maybe 30,000 to 35,000 strong—and A.D. 400, the population increased by at least tenfold. That was accompanied by a vast building program in the city in which the monarchy poured out an enormous amount of wealth, generating jobs and positions.
The second important point about Constantinople is that Constantine ensured that the bishop of Constantinople was elevated to be the equal of the pope in Rome, Saint Peter’s successor. That would cause a great deal of dispute, in time, between the western and eastern churches.
Economically, Constantinople was ideally located. It had an enormous amount of wealth coming in from trade and pilgrimages. The construction of a vast number of imperial monasteries and churches brought in the whole pilgrimage trade. Constantinople, in contrast to Rome, had a viable economic basis, which Rome did not have through most of the Middle Ages. In addition to that economic power was the fact that Constantinople was the center of a civilian bureaucratic professional class of a great city. It ensured there would be a professional government in place in Constantinople that could keep control over policy, frontiers, and armies. It could continue to tax its citizens, something the western emperors never really had. Rome certainly didn’t offer it in the 4th and 5th centuries.
From that sense, Constantine’s city ensured the continuity of a central unitary state through the Middle Ages.
Learn more: Constantinople—The Last Ancient City
The Walls that Saved the Eastern Empire
Finally, the city took on an important strategic role as well. A series of land walls, a triple defensive system, was built across the four miles of the extended city of Constantine. Cisterns were put in and there was a major aqueduct system. Those land walls made Constantinople impregnable. It’s essentially a triangle on the north and the so-called Golden Horn on the shores in the south on the Propontis, or what we call the Sea of Marmaras. Those four miles were cut off by this impressive wall structure. Towers rose to 60 feet on the inner walls while the outer walls had towers of 40 feet. There was a moat in front of it that could be flooded. All these attributes meant the city was virtually impregnable.
Strategically, that would prove essential to the survival of the eastern empire. Those walls made sure that no barbarian force ever had the means to cross over into Asia, ravage the wealthy eastern provinces, and cut the tax base. Constantinople, besides its cultural and political significance, played a very strategic role. Those walls for the next 1,000 years defied invaders and ensured the survival of the Byzantine state. When the city fell on May 29, 1453, it took 100,000 Ottoman soldiers and two months of artillery blasting to beat it down and overwhelm 7,000 defenders. They still almost didn’t take the city.
Constantine had chosen his capital well.
Common Questions about the Making of Constantinople
Constantine founded New Rome in Constantinople for many reasons. He was essentially following in the footsteps of previous rulers in locating the center of the empire near battle frontiers. Constantinople had significant geographical advantages, including a buffer in the Balkan mountains and naval access through proximity to the sea. The city was also in a prime trading zone with other nations. Constantine’s strategy was also to unite the Empire under Christianity and by removing ties to pagan Rome, he was able to do just that.
After the fall of the Ottoman Empire, the Republic of Turkey sought to distance itself by changing the name to Istanbul and renaming the capital Ankara.
Constantinople was sacked by Crusaders of the 4th Crusade. The essential reasons were greed and debt. They were in debt to Venice and seized Zara to repay. Soon after, they accepted a large reward to place Alexius back on the throne as Emperor of Constantinople. He was murdered the very next year, and Alexius Ducas replaced him. Ducas commanded the Crusaders to leave Constantinople, and they replied by ruinously sacking the city.
Constantinople was important for the expansion of the Ottoman Empire. When the Ottoman Turks took the city, it was a symbol of the rise of Islam and the fall of the center of Christianity, making the Ottoman Empire the most powerful in all of South Eastern Europe and marking the end of the Eastern Roman Empire.
This article was updated on May 12, 2020
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