Ask when the Roman Empire fell and most people will say 476 CE, when the last emperor in the West was deposed. But for nearly another thousand years, an empire ruled from the city of Constantinople continued to call itself Roman, to be ruled by emperors who traced their authority back to Augustus, and to preserve Roman law and Greek learning. It fell only in 1453. We call it the Byzantine Empire. Its people never did.

A name invented later

The people of the empire called themselves Romans, in Greek Rhomaioi, and their state the Empire of the Romans. The word “Byzantine” comes from Byzantium, the name of the ancient Greek town on whose site Constantinople was built. It was popularized by Western scholars long after the empire's fall; a German historian named Hieronymus Wolf used it in a collection of historical texts published in 1557. Later Western writers used it partly to distinguish this Greek-speaking, Orthodox Christian state from the Latin West, and sometimes to deny it the prestige of the Roman name. Historians still use the term for convenience, while remembering that it was not the empire's own.

Crisis and division

In the third century CE, the Roman Empire nearly collapsed under civil wars, invasions, plague and economic crisis. The emperor Diocletian, who ruled from 284 to 305, restored order partly by dividing the work of government, with separate rulers for the eastern and western halves. The richer, more urban, Greek-speaking East was becoming the empire's center of gravity.

Constantine

Constantine the Great fought his way to sole power over the whole empire by 324. He made two decisions that shaped the next thousand years.

First, he became the first Roman emperor to embrace Christianity. Before a battle in 312, according to his biographer Eusebius, he saw a sign in the sky and was told that in this sign he would conquer. In 313 he and his co-emperor issued the agreement known as the Edict of Milan, granting religious toleration to Christians, who had been persecuted. He supported the church with money and privileges and in 325 summoned the Council of Nicaea, the first empire-wide gathering of bishops, to settle disputes about Christian doctrine. Christianity became the official religion of the empire later in the century, under Theodosius I.

Second, he founded a new capital. In 324 he chose the site of Byzantium, on the Bosporus, the strait linking the Black Sea and the Mediterranean, at the meeting point of Europe and Asia. The city was formally dedicated on 11 May 330 and named Constantinople, the City of Constantine. It was also called New Rome. Constantine filled it with monuments, churches and statues brought from across the empire.

Why the site mattered

Constantinople was nearly ideal. Water surrounded it on three sides: the Sea of Marmara, the Bosporus and a deep natural harbor called the Golden Horn. Trade routes between Europe and Asia, and between the Black Sea and the Mediterranean, passed through it. In the early fifth century, under Theodosius II, a massive system of land walls, the Theodosian Walls, was built across the landward side. For more than a thousand years these walls, with a moat, outer wall and inner wall, made the city almost impossible to take by assault.

Life in the great city

At its height in the sixth century, Constantinople may have held several hundred thousand people, making it one of the largest cities in the world. Like old Rome, it fed many of its citizens with free grain shipped from Egypt. A grand avenue called the Mese, “Middle Street,” ran through a series of public squares lined with colonnades and shops. Aqueducts and huge underground cisterns, some still visible in Istanbul today, stored water for sieges. Greeks, Armenians, Syrians, Jews, Italians and many others lived and traded there, and visitors from across Europe and Asia described it as the greatest city they had ever seen.

East and West part ways

After the death of Theodosius I in 395, the empire was permanently divided between his two sons, one ruling the East from Constantinople and the other the West. The western half, weaker and under pressure from Germanic peoples, gradually broke up. In 476, the Germanic general Odoacer deposed the young western emperor Romulus Augustulus and sent the imperial regalia to Constantinople. The eastern empire continued.

Worked example: when did Rome fall?

Consider several possible answers and the case for each.

• 476 CE. The last western emperor was deposed. This is the traditional date in Western textbooks.
• 1204. Crusaders from the West captured and sacked Constantinople, breaking the empire's continuity for over fifty years.
• 1453. The Ottoman Turks conquered Constantinople, ending the line of emperors.
• Never, in a sense. Roman law, the Greek Orthodox Church, and ideas of empire lived on in many successor states.

Each answer reflects a point of view. Western Europeans long treated 476 as the end because their own Roman world collapsed then. Byzantine Romans would have been puzzled by the question: their empire was still there. Choosing a date is choosing a story. This course tells the story of the Romans who survived, and of how their empire preserved and transformed the ancient world.