Aydın (pronounced [ˈajdɯn]; eye-din; formerly named Güzelhisar and Tralles) is a city in and the seat of Aydın Province in Turkey's Aegean Region. The city is located at the heart of the lower valley of Büyük Menderes River (ancient Meander River) at a commanding position for the region extending from the uplands of the valley down to the seacoast. Its population was 188337 in 2010. Aydın city is located along a region which was famous for its fertility and productivity since ancient times.