ISTANBUL   
The most important reason why Istanbul has developed as a world metropolis is the geopolitical location of the city.stanbul located where the 48.north latitude and 28.east longitude intersect,is the only city in the world which is established on two continents.
The city consists of three parts in general;On the Europen side.the Historical Peninsula to the south of the Golden Horn and the Galata District to the north,and the New City on the Asian side.
The Europen side of the city is a trade and bisiness center,whereas the Asian side is more of a residential area.Istanbul is established on the both sides of the Bosphorus,which connects the Black Sea and the Sea of Marmara,and separates Asia and Europe.The 7 km.long narrow inlet,named as the Golden Horn,divides the Europen side of the city into two.Because of its location between Asia and Europe,the city always had a great geopolitical importance.
Today,Istanbul is still a political and commercial center for the Balkan and Middle Eastern Countries and the Turkic Republics of Central Asia.
The settlement,known as Byzantium after its founder,took the name Constantinople,the city of Emperor Constantine,during the reign of the Roman Emperor Constantine the Great.
It was the known as Istanbul after the conquest of the Ottomans,and became one of the biggest and most crowded city of Europe.
The city is spred over an area of 7,500 km2,long and 50km.wide.
Although its population is not occurately known,it is estimated 12 to 15 million.
THE BOSPHORUS   
Through the city's heart runs the sea channel called the Bosphorus which separates Europe and Asia. It reaches north to The Black Sea and south to the Marmara Sea,
Its shores offer a delightful mixture of past and present, splendor and simple beauty, modern hotels, wooden mansions, marble palaces, rustic stone fortresses, elegant compounds and small fishing villages