The Temple of Concordia owes its name to a Latin inscription with a dedication to 'the harmony of the people of Agrigento' found in its vicinity, albeit not associated to it.

The building, in calcarenite blocks, is in Doric style (440-430 B.C.) and is founded on a base with four steps; it has six columns at the front and back, and thirteen along the sides.

The interior of the temple was divided into three rooms: a central room called cella was preceded by a porch (pronaos) and followed by a room at the rear (opisthodomos); both the pronaos and opisthodomos had two columns in front.

On the sides of the door to the cella, there were stairs that allowed access to the roof.

The interior and the exterior of the temple were coated by white stucco with polychrome decorations.

The twelve arches on the walls of the cella and the tombs in the floor are relicts of the transformation of the temple into a Christian basilica.

The temple has survived so well because of these later modifications.

According to the tradition, around the end of the 6th century A.D., the bishop Gregorius took seat in the temple and consecrated it to the Saints Peter and Paul, after having expelled the pagan demons Eber and Raps from the building.

The persistence of a double dedication has been taken as evidence for the original dedication of the temple to the Dioskouroi: Castor and Pollux. On the spur, west of the temple, there was a Palaeochristian necropolis (3rd-6th century A.D.) linked to the transformation of the building into a basilica and which included an extensive area with rock-cut burials (sub divo) and communal catacombs with individual hypogea destined to different families.

On the eastern side of the temple, there is a series of arcosolium tombs dug into the rocky outcrop, on which the Greek period fortifications had been founded.

Numerous restorations have been undertaken since 1788, when the Prince of Torremuzza directed the removal of the remaining structures of the Christian church.

The last restorations, under the aegis of the Park Authority with European Union funding (POR Sicilia 2000-2006), have been aimed at securing the stability of the building and at conserving its stone blocks