Istanbul is the biggest city of Turkey, about 8 millions inhabitants. It is the main point-of-entry to the country if you come by air.
Planes arrive at the modern Ataturk airport (code IST), about 25km east of the city centre. There are various options for getting into Istanbul, you can take a taxi (about $10-$15), the express bus service (half-hourly, about $5 to Taksim),or a metro to Aksaray, and a tram on to Sultanahmet.
International trains from across Europe arrive at the Gar in Emionu, close to Sultanahmet. Asian trains arrive at Haydarpasha station. To get between the two, catch a ferry across the Bosophorous (see Get around).
Buses and coaches terminate at the colossal Otogar, about 10km east of the centre. Courtesy minibuses or taxis will easily get you into the centre.