Istanbul is the largest Turkish city with a population of over 15 million. During the high season, the number of people walking the streets of the city can increase by 1-2 million. Therefore, it is not surprising that Istanbul has two operating international airports (Istanbul Airport and Sabihi Gökçen Airport). Ataturk Airport, Istanbul's oldest airport, has been closed permanently since the introduction of İstanbul Havalimanı. Full conservation of its building is expected to take place in 2022.