Sagalassos, also known as Selgessos and Sagallesos, is an archaeological site in southwestern Turkey, about 100 km north of Antalya, and 30 km from Burdur and Isparta. The ancient ruins of Sagalassos are 7 km from Ağlasun in the province of Burdur, on Mount Akdağ, in the Western Taurus mountains range, at an altitude of 1450–1700 metres.
In Roman Imperial times, the town was known as the "first city of Pisidia", a region in the western Taurus mountains, currently known as the Turkish Lakes Region. During the Hellenistic period it was already one of the major Pisidian towns.