The temple’s name derives from a Latin inscription dating from the early imperial age and carrying a dedication from the town of Agrigento to the Concord, which was situated nearby and which, erroneously, was assumed to refer to the building. The temple, however, is one of the best examples of the Doric style and dates from 440-430 B.C. Its state of preservation, due in part to the fact that the temple, at the end of the 6th century A.D., was transformed into a Christian Church, is exceptional, allowing the visitor to admire and analyse its details. It is an excellent example of the wonderful development and harmonious beauty achieved by the Doric temples in general during their peak. Raised on a base which, as in the Temple of Juno, is designed to compensate for the unevenness of the ground, we find the crepidoma, composed of four steps. This in turn acts as the support for the temple’s main elements, composed of a peristyle and cell. The peristyle columns (6 × 13 with 20 canonical-type flutes: 6.72 m height) are harmoniously cylindrical: after a slight thickening which reaches to approximately a third of their height from the stylobate (entasis), they narrow significantly toward the top of the shaft, where the lines lengthen again in the prolonged, soft curve of the capital’s echinus. As confirmed by precise measurements effected in other temples, the system of proportions applied by its anonymous builder is complex and subtle, designed to achieve a perfection that, while difficult to define, indicates the presence of a miraculous, never-exceeded architectural style that is simple and elementary in appearance only. Even a cursory glance reveals the existence of curvatures that develop the lines of the solid base. The elegant columns, elastic and wrapped in an aerial atmosphere, vibrate with the imperceptibly helical line of their flutes, the inclination towards the four walls of the cell and the corners, and with the modulated width of their inter-axles. These details find their perfect response in the rational modulation of the dimensions of the metopes and triglyphs, whose alternation in the frieze reaches a sublime compositional clarity. Of the entablature, which is preserved in its entirety on the two fronts, mention must be made, as well as of the frieze, of all the other elements, including the typical mutuli cornice: unique in Sicily and extremely rare in any other location. The cell, measuring 28.36m in length and 9.44 in width, and which is accessed by a step, also consists of an opisthodomos and a pronaos, both with pilasters (in antis). Both the square pylons between the pronaos and the cell and the internal steps leading to the ceiling are well preserved. The isodomia of the structures is in perfect condition, having suffered no damage with the passage of time. Upon the disappearance of the rear wall of the cell, the ceiling collapsed completely, although its different parts can be easily recognized through the study of the cavities for the insertion of beams which are visible in the cell walls and on the entablature blocks. A slight flight of fantasy is required to be able to imagine this temple as it was seen by the Greeks of the 5th century B.C. At that time, it was completely covered with plaster: white on the lower parts of the base and the column shafts and bright and variously coloured from the capitals up. Green, red, brown and blue were the colours used to give visibility and characterization to the structure’s different elements. We must also mention the fact that even the metopes, rather than being carved as in some temples of Selinunte, and in Doric temples in general, were painted with mythological scenes referring to the deity to which the temple was dedicated. The roof was made with marble tiles, which were also coloured. Gutters topped off with lions’ heads extended from the ogee. In a triumph of motifs and colours, polychrome antefixes, acroterions, and palmettes make up the festive, auxiliary components which beautifully decorate this sober building. There is no surviving information relative to the fronts: however, it is highly unlikely that the tympanums’ triangles were originally empty. They were most probably occupied by long-since disappeared painted or sculpted ornamentation. The 12 arches that penetrate into the two sides of the cell walls are the remains of the adaptations suffered by the temple at the time of its transformation into a Christian basilica. At the end of the 6th century A.D., Bishop Gregorio adapted the function of the old pagan temple, dedicating the new church to the Saints Peter and Paul. And the orientation of the building was then reversed. The wall that divided the cell from the opisthodomos was demolished; the space between the columns was filled with compact walls; and the basilica was divided into three naves, with the central nave being represented by the old cell. Within this new context, the temple’s front altar had to be destroyed, for obvious reasons of incompatibility, with no remains having survived. The restoration of the monument to the condition in which the original forms of the classical era have been preserved dates from the 13th century, with the work having been ordered by Ferdinand III of Bourbon in 1788.