The acropolis of the city named Byzantion was located in the area where today the Topkapı Palace stands. Today its agora coincides with present day Ayasofya. A hippodrome was built in the yaer 196 on some flat land terracing down to the Marmara Sea, which was later known as At Meydanı (Square of the Horses). The city walls were passing just outside the palace. During the reign of Constantinus I, when significant construction activities were undertaken in the city, the old city walls were brought down and new ones were built which bounded a larger area. The city which continued its growth in subsequent years eventually spilled out of these walls. This led Emperor Theodosius II to build part of the city walls of İstanbul which have lasted up to present times.

In that period, houses were located on the sections of the area surrounded by the walls which faced either the Golden Horn or the Marmara Sea, while commercial facilities were located around the Sirkeci area and administrative, religious and commercial centers concentrated at Sarayburnu, Beyazıt, Aksaray, Cerrahpaşa and Yedikule. A new settlement area had developed on the other shore of the Golden Horn at Galata. The majority of the inhabitants of this settlement, which was called Sykai (Sycae) were Venetians and the Genovese. Surrounded with later built city walls, the area became a rich commercial center.

The first bridge on the Golden Horn was built by Justinien, a connection between Ayvansaray - Kasımpaşa to make Skyai easily accessible. Galata was given to the administration of the Genovese in 13 th century and sustained its commercial significance for centuries. In the 5th century, the city was one of the major cities of the world, with its population reaching 100 thousand. When 14 th century was reached, Constantinopolis was the administrative center of an empire whose boundaries had shrunk considerably and whose inhabitants were mostly involved with agriculture. Its population, which was around 50 thousand when conquered by the Ottomans, became more than 100 thousand when the Muslim and non - Muslim groups removed from Anatolia and Thrace and beyond (Rumeli) During this period, the majority of the Muslim population was living outside the peninsula were the old city was located. During the Ottoman period the population of the city grew even further, and the city also expanded physically. Skyai also bursted from the city walls and grew towards the Pera area (currently Galatasaray)

In the 19th century, significant developments were seen in Galata. While this section of the city preserved its importance as a commercial center, it started to achieve the characteristics of a European city, as foreign embassies, foreign banks, and foreign insurance firms and commissioners concentrated here and recreational facilities started to increase in number. The move of Ottoman Sultans from Topkapı Palace to the Dolmabahçe palace near Galata also took place in this century. Later, other palaces were built both in this area and on the shores of the Bosphorous. New settlement areas were also established around Kadıköy and Üsküdar.

Feshane, (the fez factory) which was the first significant industrial establishment of its times, was commissioned in the Golden Horn area. In the 19th century, the city had new means of transportation such as railways, trams, and a mini - metro, (the tunnel) both at the urban and intra - urban scale. While the port was being modernized, ferry operations were started along the Bosphorous. Railway connections were made to İzmit and Edirne, and suburban lines were being provided to connect the city to its immediate surroundings. The bridges connecting the two shores of the Golden Horn were also built in this century. In 1854, the Municipality of İstanbul was established.

Taking the rapid urbanization the city displayed into consideration, several plans were drawn up for the city during the Republican Period. When these plans allocated the areas around the Golden Horn and the Bosphourus to industry. Starting in 1940, these areas were filled with factories and business activities. Due to the exodus to the cities which started at a major scale in 1950s, reaching larger dimensions with the arrival of migrants from Balkan countries, these industrial districts started to be surrounded by squatters. The same trend was experienced on the Anatolian side, around Maltepe, Kartal and Pendik.

The expansion of industrial and settlement areas has drastically changed the visual look of İstanbul over the past 30 years. With a rapidly growing population and constantly changing settlement boundaries, establishment of numerous new administrative districts became inevitable. The Central District which has become a dense commercial area, losing its residential functions, now experiences an incredible fluctiation betwen its day time and night population also lost its administrative significance. Hence İstanbul does not posses an administrative central district similar to those seen in Ankara and İzmir.

The major educational institutions located in İstanbul are the Boğaziçi, İstanbul, İstanbul Technical, Marmara, Mimar Sinan and Yıldız Universities. İstanbul is a cultural center of international character, and each year several festivals are organised including film and drama festivals and major concerts are given.

Istanbul also has the honour of being the cradle of the innovative mode of urban transportation called "dolmuş" (shared taxi) Turkey which is also seen in other cities of Turkey and some cities of the world.