The ancient site of Nyssa is located on the slopes of Mount Malgac (Mesogis) in Sultanhisar, at 30 km east of Aydin city (ancient Tralles). According to Strabo, a Greek geographer, the city was founded around 3rd century BC by Seleucids and its earliest name was Athymbra. It was flourished as a science and teaching center. There was a stream running through the city dividing it into two parts, and the same stream was passing from a tunnel under the theater.
Amongst the structures of the ancient city we can count a gymnasium, a library built by Aristodem, an agora surrounded by porticos, a well preserved bouleuterion, the necropolis, Hellenistic water cistern, a Roman stadium and a bridge, a 12 thousand seat capacity and 2nd century fine Greco-Roman theater with a 200 meter long water tunnel underneath. Almost nothing left from the Hellenistic city walls, and only few sections of the Byzantine walls survived.
There is another ancient site of Nyssa in Anatolia, that's in Muskara town of Nevsehir province and its foundation dates back to the Hittite period. This Nyssa was a titular see in Cappadocia during the times of early Christianity in Asia Minor from which there is a well known Christian bishop and saint, St. Gregory of Nyssa.