| BEST WAY DOWNTOWN:
Ataturk International Airport is located 15 miles (24 km) west of downtown Istanbul.
Taxis to Taksim Square and most of the major hotels will cost about 600,000-730,000 Turkish lira ($13 to $15). Taxis to the old city, Sultanahmet (near St. Sophia), will be about 525,000-650,000 Turkish lira ($11 to $14). The trip will take from 30 to 45 minutes (approximately). The Turkish lira is subject to wild fluctuations, so check for the current exchange rate on your arrival.
Consider taking a Dolmus, a shared taxi as big as an old Buick or mini-bus. The Dolmus rates between a bus and taxi in terms of comfort and price (it is more comfortable than a bus, and less expensive than a taxi). Since Dolmus drivers wait until all seats are filled, the ride is less speedy than in a taxi, but who knows, the company might prove interesting.
The Havas airport buses go between the airport and the Turkish Airlines City Terminal. The city terminal is near the Galata Tower, which is a short taxi ride to either Taksim Square or Sultanahmet.
Buses depart from the airport every half-hour during the morning (5:30 A.M.-10 A.M.) and evening (2 P.M.-8 P.M.) travel peaks, and every hour at other times. The bus will cost around 160,000,00 Turkish lira ($3) and take 30 to 50 minutes for the trip. So combined with a short taxi ride in the city, this is a good deal.
Avis, Budget, Europcar, Hertz, and Interrent, all have offices at the airport arrivals hall and at points in the city, including some hotels.
World Airport Information Main Page
Adapted from How to Get Out of the Airport