The church of St. Saturnino in Cagliari, Sardinia, Reading the levels of history through the use of digital survey and the petrophysical study of materials

The most ancient church in Cagliari is dedicated to Saint Saturno (commonly named Saint Saturnino), the first indications about this church come from the sixth century, but the building arrived to our time is only a part of the original one and it rises over the ruins of previous structures, inside a walled area with the presence of a Palaeo-Christian necropolis. The original Greek cross plan, with a transept and a semi-spherical dome, has seen meaningful transformations in time, with the partial destruction of large parts of the building. All the four arms had a nave and two aisles, but the current church consists only of the domecovered part and of the eastern arm, with a nave and two aisles. The whole church shows very interesting spoils coming from previous architectures of the Roman age, a rich catalogue of materials and details. In summer 2013, a collaboration between the Departments of Chemical and Geological Sciences from Cagliari and the one of Architecture from Florence brought to the realization of a detailed study about this ancient church. The whole building and its surrounding area were surveyed with the following methods: photography, 3D Laser Scanner for the whole interior and exterior parts, photogrammetry of a selected set of stone surface samples, direct sampling of significant rocks and their geochemical and petrophysical analysis. All data were then treated and analysed to deepen the knowledge about the most meaningful aspects of different construction techniques and use of materials, provenance of raw materials, stone and structure alterations. As result, a base was created to read common features, design choices, recursive constructive solutions, and the “models” guiding the ancient intentions. This contribution will present the progress state of this research and its results.