Nova Roma
Celebrating his victory against the eastern Roman Emperor, Licinius, Constantine 1 has Byzantium renamed Nova Roma - New Rome. The original Constantinople was surrounded by seven hills, just like Rome. 6 crests lies along the Golden Horn, while the 7th lies alone about a km south.
Constantine built his new capital with the help of artisans from Rome, so Constantinople retained a lot of Roman classical art.
The Roman Empire was officially split into two parts, the East and the West in 395 C.E. In 476 C.E. the Ostrogoths removed the Western Roman Emperor Romulus Augustus from the throne and thereby returned the entire Empire to Zeno, the Eastern Roman Emperor. This transfer of power marked the downfall of the Western Roman Empire and Constantinople’s establishment as the single imperial capital. Thereafter, the Eastern Roman Empire became known as the Byzantine Empire, and Constantinople became a uniquely eastern Orthodox city.
Constantinople was the capital and the greatest city in Christendom in terms of wealth, population, and political power. The Empire it ruled consisted of Asia Minor, the Balkans, and Greece. Over the 12th and 13th centuries, it lost most of its lands in all these areas, but its fortunes waxed and waned dramatically. By 1291, however, the "Empire" was reduced to the city of Constantinople and its hinterland, plus a few outposts.
The great city, Constantinople, fell to the hands of the Ottoman Turks on Tuesday 29th May 1453.
Map of Constantinople (1422)
That was a great shock to the whole Western Europe. Since that day, it has been called Istanbul as Sultan Mehmed II declared in Haiga Sophia, praying to Allah, 3 days later: "Here after my capital is Istanbul" [Sir Edwin Pears, "The Fall of Constantinople being The Story of The Fourth Crusade"]
"Woe be to thee, O Constantinople,
seated on seven hills,
thou shall not continue a thousand years."
["The Antiquities of Constantinople" by Pierre Gilles, translated by John Ball, p.180
Constantinople 18th Century