Ataşehir is a municipality and district of Istanbul Province, Turkey. Its area is 25 km2, and its population is 423,127 (2022). It is located at the junction of the O-2 and O-4 motorways on the Anatolian (Asian) side of Istanbul. Its neighbours are the districts of Ümraniye to the north, Sancaktepe to the northeast, Maltepe to the east, Kadıköy to the south and Üsküdar to the west.

Otoyol 2, abbreviated as O-2, locally referred to as 2. Çevreyolu, is a motorway in Istanbul, Turkey that forms the outer ring road of the city connecting European and Asian parts via the Fatih Sultan Mehmet Bridge.