On this remarkable site at the end of the colonnaded street, overlooking the Lower Agora, a temple was built in the reign of Emperor Augustus (27 BC-14 AD) to honor Apollo Klarios. (Klarios was an oracle shrine of Apollo, near Ephesus.) At first, this small lonic temple only had half-columns on its front façade (and possibly on its back façade as well!.
Before the temple was built, Apollo was not one of Sagalassos's main gods. But Augustus favored Apollo, believing that he was his protector. Building a temple to Apollo, then, was also a way of honoring the Emperor himself.
From the reign of Vespasian (69-79 AD) onwards the building served as the official imperial cult temple, making the connection official. Soon after 100 AD it was renovated, partly with private money. The interior was clad with marble and columns were erected on four sides of its exterior. This was one ne way that the Imperial cult had a visible influence on the development of Sagalassos.
After the Temple of Hadrian and Antoninus Pius was built, the Temple of Apollo Kiarios played a secondary role in worship of the Emperors, and fell out of use by 400 AD. Around 450, the building was rebuilt as a Christian basilica, using the stones of the temple. Excavations have shown that after the church went out of use it was used to deposit trash. Later, between the 10th and 15th centuries AD, it was used as a Christian cemetery by people living nearby.