The stadium was a spectacle building. In plan, this long building had a semi-circular end. Rows of stone seats were arranged on top of a podium and surrounding a running track of approximately 145 metres long and 25 metres wide. As its remains are largely buried underneath the Ottoman road from Ağlasun to Isparta, only few traces of the stadium are currently visible.
Built during the second half of the 1st century CE, it functioned as the venue for athletic competitions. These were not just sports events but were organized as part of religious festivals, such as the Klareia in honour of the god Apollo. Also gladiator fights and animal hunts could take place here, as part of the festivals of the cult of the Roman emperors.
When these ancient competitions and spectacles lost their popularity as result of the rise of Christianity in Late Antiquity, the open space of the arena was occupied by two churches. The Christian basilica near the entrance of the old stadium was the largest church of Sagalassos. The church was erected during the second half of the 5th or early 6th century re-using building blocks from at least three different buildings. These include the temple dedicated to Roman emperors and a small Corinthian sanctuary, that was tentatively identified as a temple for Dionysos. The figural friezes depicting masks of maenads and silens on the outside and dancing satyrs on the inside of the transept of the basilica were most probably recuperated from this old Dionysos temple.
The churches inside the stadium were part of a large Christian sanctuary that can perhaps be related to the worship of a Christian martyr who met his end in the stadium. The city of Sagalassos later transformed the place of execution into one of pilgrimage.