Humanities › History & Culture Constantinople: Capital of the Eastern Roman Empire Share Flipboard Email Print Alexander Spatari / Getty Images History & Culture Ancient History and Culture Rome Figures & Events Ancient Languages Greece Egypt Asia Mythology & Religion American History African American History African History Asian History European History Genealogy Inventions Latin American History Medieval & Renaissance History Military History The 20th Century Women's History View More By N.S. Gill Ancient History and Latin Expert M.A., Linguistics, University of Minnesota B.A., Latin, University of Minnesota N.S. Gill is a Latinist, writer, and teacher of ancient history and Latin. She has been featured by NPR and National Geographic for her ancient history expertise. our editorial process N.S. Gill Updated January 14, 2020 In the 7th century BCE, the city of Byzantium was built on the European side of the Strait of Bosporus in what is now modern Turkey. Hundreds of years later, the Roman emperor Constantine renamed it Nova Roma (New Rome). The city later became Constantinople, in honor of its Roman founder; it was renamed Istanbul by the Turks during the 20th century. Geography Constantinople is located on the Bosporus River, meaning that it lies on the boundary between Asia and Europe. Surrounded by water, it was easily accessible to other parts of the Roman Empire via the Mediterranean, Black Sea, Danube River, and Dnieper River. Constantinople was also accessible via land routes to Turkestan, India, Antioch, the Silk Road, and Alexandria. Like Rome, the city claims 7 hills, a rocky terrain that had limited earlier utilization of a site so important for sea trade. History of Constantinople Emperor Diocletian ruled the Roman Empire from 284 to 305 CE. He chose to split the huge empire into n eastern and western parts, with a ruler for each portion of the empire. Diocletian ruled the east, while Constantine rose to power in the west. In 312 CE, Constantine challenged the rule of the eastern empire, and, upon winning the Battle of Milvian Bridge, became sole emperor of a reunited Rome. Constantine chose the city of Byzantium for his Nova Roma. It was located near the center of the reunited Empire, was surrounded by water, and had a good harbor. This meant it was easy to reach, fortify, and defend. Constantine put a great deal of money and effort into turning his new capital into a great city. He added broad streets, meeting halls, a hippodrome, and a complex water supply and storage system. Constantinople remained a major political and cultural center during the reign of Justinian, becoming the first great Christian city. It went through a number of political and military upheavals, becoming the capital of the Ottoman Empire and, later, the capital of modern Turkey (under the new name Istanbul). Natural and Man-Made Fortifications Constantine, the early fourth-century emperor known for encouraging Christianity in the Roman Empire, enlarged the earlier city of Byzantium, in CE 328. He put up a defensive wall (1-1/2 miles east of where the Theodosian walls would be), along the westward limits of the city. The other side of the city had natural defenses. Constantine then inaugurated the city as his capital in 330. Constantinople is almost surrounded by water, except on its side facing Europe where walls were built. The city was built on a promontory projecting into the Bosphorus (Bosporus), which is the strait between the Sea of Marmara (Propontis) and the Black Sea (Pontus Euxinus). North of the city was a bay called the Golden Horn, with an invaluable harbor. A double line of protective fortifications went 6.5 km from the Sea of Marmara to the Golden Horn. This was completed during the reign of Theodosius II (408-450), under the care of his praetorian prefect Anthemius; the inner set was completed in CE 423. The Theodosian walls are shown as the limits of the "Old City" according to modern maps. Source The Walls of Constantinople AD 324-1453, by Stephen R. Turnbull.