During 4th century A. D., Roman Empire had been expanded too much, and Istanbul is selected as the new capital city instead of Roma by Emperor Great Constantine due to its strategic position. City is re - organized within a period of exceeding 6 years, its ramparts are widened and lots of temples, official buildings, palaces, hamams and hippodrome is constructed. With great ceremonies, performed on 330, city's being the capital city of the Roman Empire is officially announced. During the period when Near Age had begun, the city which is also known as Second Rome and New Rome, is then named as "Byzantion" and Constantinople in the late eras. Name of the city is mentioned as "Polis" among the public in the course of time.

It is seen that efforts of making city beautiful of the emperors after Great Constantine is continuing. First churches within the city are constructed after Constantine. Istanbul remain the capital city of Eastern Roman Empire (Byzantine) for a long period due to the fall down of West Roman Empire on 5th century. The city, which is re - constructed during Byzantium period are re - widened with ramparts. Today, 6492 m. long magnificent city ramparts are constructed by Emperor II. Theodosius. In the city, whose population is exceeding half million on 6th century, one more golden age is lived under Emperor Justinyen reign. Famous Hagia Sophia, which remained till today, is the piece of art of this Emperor. Byzantium Empire and capital city Istanbul's latter history is full of palace and church intrigues, Iran and Arab attacks and frequently changing emperor families' bloody fights.

Latin reign, which is adark age between726 - 842, had begun with the conquer of city by Crusaders on 1204, 4th Crusade, and city is raided for years till to the all churches and monasteries as well asmonuments. The city, whose reign is passed to Byzantium again on 1261, did not gain its former richness again. City is conquered by Turks on 1453 after a 53 days siege.

Gargantuan canons, used for the first time in the war history by Fatih Sultan Mehmet, are reasons of surpass of Istanbul ramparts. Capital city of Ottoman Empire had moved to this place, population of the city is increased with the immigrants, imported from various parts of the country, and public improvement studies of the desert and demolished city had been commenced. Religious freedom and social rights are given to the former residents of the city, and let them to continue their lives. Patriarchate, which is the head of Christian Orthodox Church, remains till today due to the rights given by Fatih. Turkish art stigmatized the city one century after conquer, and domes and minarets have reigned the panorama of the city. Beginning from the 16th century, due to being Ottoman Rulers Caliph at the same time, Istanbul also become the center of Islamic world.

City is fully improved under the reigns of Sultans, and gain a miracle atmosphere. There are frequent fires, which demolishes wide areas within the colorful pages of Istanbul history in this period. Sultan Palace, which is constructed in former acropolis, is reigning the unique panorama of Bosporus and Golden Horn. After denser connections with Western world, beginning from 19th century, mosques and palaces begun to be constructed to Bosporus coasts with European architecture style. Lots of palaces, constructed within a short period of time, are also the symbols of the falling down period. Istanbul, was one of the witnesses of another world empire, conclusion of the I. World War.

While empire is divided, and internal and foreign enemies were fighting for their shares, a noble commander of the Turkish army had entered into a struggle for Turkish nation. This Mustafa Kemal named national hero, after Independence War exceeding 4 years, republic of Turkey is established on 1923 by him. Moving the capital city to Ankara, did not change the importance of Istanbul. This unique city is continuing to its life with its charming appearance.