The new Temple of Apollo was established above the ancient and holy chasm called Plutonium was the oldest religious centre of the native community, the place where Apollo met with Cibele. It was said that only the priest of the Great Mother could enter the cave without being overpowered by the noxious underground fumes. The remains of the superstructure of the Temple of Apollo date from the 3rd century AD while the foundations are late Hellenistic.

The Temple, which may be recognised by its marble staircase, lies within a sacred area, about 70 metres long, which was surrounded by an enclosure wall (temenos). The enclosure was in turn surrounded, at least on its southern, western and northern sides, by a marble portico which has been only partially excavated.

An elegant marble portico may be seen, with pilasters bearing fluted Doric semi-columns supporting capitals that are decorated below with a row of astragali and beads and which, on the decorated below with a row of astragali and beads and which, on the echinus, bear a series of ovolos.

The structures of the Temple are later, though the presence of two beautiful Ionic capitals in the Museum (see under Museum), as well as of a Corinthian capital of the first century AD and other architectural fragments lead us to suppose the existence of an earlier temple on the site.