I can think of two main reasons; -Istanbul is the biggest city of Turkey and therefore has a large tourism base. The requirements to cope with the mass of passengers means the airport would have to be larger than a standard airport. -Istanbul is one of the only settlements in the world that has a continental border and therefore have too have higher standards for Immigration control. I hope this help's you.
Most likely you will land in Istanbul Atatürk. Sabiha Gökçen is a domestic airport.
Istanbul is the most important one as Turkey's culture and business centre without a doubt. Ankara, Izmir, Antalya and Bursa are the other important cities.
The most populated cities in Turkey are Istanbul, Ankara, and Izmir. Istanbul is the most populous city in Turkey, followed by the capital city of Ankara, and then Izmir.
Istanbul is the most populous and historically-rich city in Turkey. Ankara is the political capital. Between those two, which one is more important is really up to personal preference.
Istanbul.
Most of Turkey is in Asia, a small part of it (west of Istanbul) is in Europe.
İstanbul is the most crowded city of Turkey - not a country. And Turkey is a Democratic Republican Country. People vote for the political parties just like most countries in Europe.
İstanbul
The most outstanding attraction is Istanbul.
The Haghia Sofia in Istanbul is among the most famous landmarks in Turkey.
Izmir is the third most populous city in Turkey, after Istanbul and Ankara. Ankara is the capital of Turkey.
The main religion in Istanbul is Islam, as most of the population is Muslim. However, there are also significant Christian and Jewish communities in the city.