Constantinople was the imperial capital of the Roman Empire (330–395 A.D.), the Byzantine (Eastern Roman) Empire (395–1204 A.D. and 1261–1453 A.D.), the Latin Empire (1204–1261 A.D.), and the Ottoman Empire (1453–1922 A.D.). The city was also known as New Rome.
The city itself is located in a strategic geographic position. Constantinople is between the Golden Horn and the Sea of Marmara at the point where Europe meets Asia. It's location provided the eastern provinces of the old Roman Empire a defense against the barbarian invasions of the 5th century.
For many years during the Middle Ages Constantinople had an advanced economy and was Europe's largest and wealthiest urban center in the Eastern Mediterranean. This was mainly due to its strategic location (where Europe meets Asia) and its role as one of the primary ports for the famous Silk Road (route that facilitated trade between China, India, Egypt and Europe) which made it a wealthy economic hub. Byzantine Constantinople also boasted a large amount of artistic and literary treasure before it was sacked in 1204 and 1453.
The city was originally founded as a Greek colony under the name of Byzantium in the 7th century B.C. Roman Emperor Constantine I, wanting to transfer his capital away from Nicomedia (in Anatolia), choose Byzantium on the Bosphorus as the new center of the empire. In 330 A.D., after six years of building, the city was consecrated and officially made the new capital of the Roman Empire. It was only after the death of Constantine that the city was renamed Constantinople.
Roman (Byzantine) Emperor Justinian I, from Constantinople in 533 A.D., began his expedition for the retaking of the former Diocese of Africa. In the 730s Roman Emperor Leo III carried out extensive repairs of the city's walls, paid for by a special tax that was levied on all the subjects in the Empire.
Although attacked several times by a variety of people Constantinople was only taken three times. In 1204 A.D. the city was taken by the army of the Fourth Crusade and in 1261 A.D. by Michael VIII. Both times the city was sacked of its significant amount of artistic and literary treasures. In 1453 A.D. Turkish sultan Mehmed II "the Conqueror" conquered the city for the Ottoman empire.
The Ottoman sultans embellished the city with many beautiful mosques, palaces, monuments, fountains, baths, aqueducts and other public buildings. After World War I, the city was occupied (1918 to 23 A.D.) by the Allies. In 1922, the last Ottoman sultan was deposed and in 1923 Ankara became the new capital of Turkey. Constantinople was officially renamed Istanbul, which means "in the city" or "to the city," in 1930 A.D.