Istanbul is an amalgam of both East and West; European and Middle Eastern. This is not merely a metaphor, the city is bisected by the Bosporus Strait, with the western half situated in Europe and the eastern half in Asia. Formerly Constantinople, Istanbul was one of the last holdouts of the Eastern Roman Empire before falling to the Ottomans in 1453. The Ottomans would later meet the same fate in 1922, when Mustafa Kemal Ataturk and his cohorts finally overthrew the Sultan and established the Republic of Turkey the following year. This history is important, as it both explains the unique character of the city and of the country as well. Tourists would do well to avoid criticism of Ataturk or of Turkishness in general, as both are, at best, frowned upon, and at worst, legally actionable.
With such a rich history, the sites to see in Istanbul are numerous. Some of the main highlights include: The Grand Bazaar, Sultanahmet Square, The Blue Mosque, and the Hagia Sophia. Nearby, you can walk down the famed Istiklal Avenue, which is home to scores of shops and eateries, as well as a number of street peddlers and musical acts.
Food is a major part of the culture of Istanbul, with a seemingly endless number of places to get Doner Kebab, pide, loaded baked potatoes, kofte, or the famous Iskender Kebab. Tea is also a huge part of the Turkish dining experience, with complimentary tea after a meal being standard at many restaurants.
Should you desire a stronger drink, there is plenty of nightlife around Istiklal and the central Taksim Square. While out on the town, do not neglect to eat the stuffed mussels served on the street. The city also has plenty of taxis to get you where you need to go, and an extensive public transportation system which uses reloadable cards for trams, buses, the underground, and ferries. The highlight is, of course, the ferry system which takes passengers across the Bosporus from the Asian side to the European side and vice versa. Also, delicious fish sandwiches and Turkish simit are sold at the piers, making this one of the most pleasant commuting experiences you may ever experience.
Istanbul is serviced by two airports, though flying into Istanbul Ataturk Airport is the most convenient airport to fly into, since the station is serviced by the rail system, which will take you to the European part of the city.