Istanbul is settled on both sides of the Bosphorus which separates Asia and Europe continents. It is the most crowded city with the population  of over 18 million. It was the capital of Roman, Byzantine and Ottoman Empires, and built up with magnificent religious and civil monuments for ages.

The first foundation of the city are told in legends: in 650 B.C. a sea tribe under the leadership of Byzas set sail from Megara and established Byzantium around today’s Seraglio Point (Sarayburnu). City, which took the wrong side in a fight for throne in 191 B.C., was conquered and razed by Roman Emperor Septimius Severus after a siege for two years. The city was rebuilt and expanded by the same emperor, and new walls and buildings had been built.

Great Emperor Constantine (306-337) chosen the city as new capital, comprehending the importance of its magnificent strategic point where is the intersection of the land and sea routes. In more than six years city expanded by the rebuilt of the walls, and after the construction of many temples, official buildings, baths and hippodrome, it had been officially became the capital or Roman Empire in 330 A.D. with a great ceremony. With the start of a golden era, city was named Byzantium and in the late periods Constantinople after they were named Second Rome and New Rome which were forgotten soon.

Even Roman Empire was divided in 395 and Western Roman Empire was demolished in the 5th century, Eastern Roman Empire continued its existence for more than a thousand years under “the administration of the capital Istanbul. Modern historians name this empire as “Byzantine Empire”.

Istanbul was expanded again after the reconstruction of the walls in first half of  the 5th century. The walls that the magnificence still can be seen were made by Emperor Theodosius II (408-450) and its length is 6492 meters. In the 6th century with over half a million population, city lived another golden age with Emperor Justinian (527-565). Famous Hagia Sophia is a work of this emperor.

Latin domination which is a dark period of its history started with the invasion of the city with the 4th Crusade in 1204, and all churches, monasteries and monuments had been robbed for years. Even Byzantines took over the city in 1261 again; the city never met his old wealth again. Threat of Turkish Ottoman Empire, which was growing and expanding, had increased and after a 53-day siege, Turks conquered the city in 1453.

Sultan Mehmet the Conqueror increased the population of the city by bringing migrants from different parts of the country after making the city capital of Ottoman Empire, started the construction works of empty and devastated city. He provided to live their life by giving freedom of religion and social rights. The Christian Orthodox Church Patriarchate has remained by these primary rights. Hagia Sophia and some other churches transformed to churches and rescued from squalid conditions.

Istanbul was developed and reconstructed in a short time after it was taken over by Turks. A century after the conquest Turkish Art marked the city, domes and minarets dominated the silhouette of the city.

After the frequent contacts with the Western World in 19th century, mosques and palaces started to be built near the shores of the Bosporus in the style of European architecture.