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The theater of the ancient city of Akragas has been researched for centuries and, in 2016, a multidisciplinary and multi-scale research work that involved topographic studies, analysis of satellite images, geomorphological characterization of the land, archaeological surveys, and non-invasive geophysical surveys led to its discovery. In this work, a comparison between the archaeological structures hypothesized by geophysical results and the archaeological structure excavated is presented. The area of about 5.500 m2 was investigated using electrical resistivity tomography (ERT). The survey highlighted a series of resistivity highs arranged on concentric semicircles defining perfectly the presence of an articulate building attributable to a theatrical complex of imposing dimensions (diameter of about 95 m). Archaeological excavation led to the identification of the summa cavea with the discovery of foundation-level structures arranged on a semicircle, on which the tiers were located, and cuts in the rock with seat imprints. The overlap of the technical layouts obtained from the documentation of archaeological excavation on the modelled resistivity maps shows the perfect correspondence between the features of the resistivity highs and the ancient structures actually found.

Protection and conservation are not feasible without a deeper knowledge of the cultural heritage of the subject of intervention. A careful analysis of documentation, a detailed visual inspection of surfaces, and a systematic diagnosis of the inner properties are the basis for planning preventive strategies of restoration. Digital noninvasive techniques represent an advantageous tool with useful outputs to estimate the state of health of cultural heritage in order to minimize the progress of degradation. This paper deals with a 3D metric survey through photogrammetry and ground-penetrating radar (GPR) tests applied to the study of the trapezophoros with two griffins attacking a doe of Ascoli Satriano, a masterpiece of ancient art that needs to be protected. This work provided information on both visible and hidden defects, such as numerous cracks that affect the sculpture.