Istanbul is Europe's most populous city (the world's 4th largest city proper and 20th largest urban area) and Turkey's cultural and financial center. The city covers 27 districts of the Istanbul province. It is located on the Bosphorus Strait, and encompasses the natural harbor known as the Golden Horn, in the northwest of the country. The city was chosen as joint European Capital of Culture for 2010. The historic areas of Istanbul were added to the UNESCO World Heritage List in 1985.
Old Istanbul includes all the traces from Byzantium, Roman and Ottoman periods. The huge Basilica of Hagia Sofia is an incredible museum today. It opens 9am-5pm Tue-Sun, upper gallery till 4.30. The Topkapi Palace is a good example to understand Ottoman life . It opens 9am-5pm Wed-Mon. There are many churches, mosques and museums at this district.
When you pass over Galata Bridge from Eminonu, you will reach Beyoglu the most well-known avenue with nightlife. Taksim Square is the heart of modern Istanbul.
The other glamorous districts are Nisantasi for shopping with the every famous textile brands like Paris of Istanbul and Besiktas with beautiful bosphours view.
Bostanci and Kadikoy are the modern places on the Asian side. From Kadikoy there are ferries to the islands. Maiden’s Tower is worth to see and reachable by ferry.
Istanbul bus station is Esenler, about 10km west of the city centre; Ataturk International Airport is in Yesilkoy, 23km west of Sultanahmet.