Investigating the urban archaeological sites using Ground Penetrating Radar. The cases of Palatino Hill and St John Lateran Basilica (Roma, Italy)

The geophysical prospection is generally considered as the attempt to locate structures of archaeological interest buried in the natural subsoil, but in many cases, when applied in urban centers, this attempt could fail due to the effect and disturbances caused by recent man-made structures in the subsoil, covering any signal related to possible archaeological structures. In the present paper the GPR surveys carried out in two urban archaeological sites in Roma, characterised by different targets and environmental conditions, are presented and discussed. The first site, a portion of Palatine Hill (archaeological center area of Roma) is characterized by natural soil on the surface and an overlapping of many archaeological structures in its volume. The second site, St. John Lateran Basilica (Roma), is characterized by artificial medium as road pavement, outside the basilica, and ancient buildings, below the actual basilica. The paper illustrates the two GPR surveys and the obtained results.