GNGTS 2016 - Atti del 35° Convegno Nazionale

572 GNGTS 2016 S essione 3.2 Fig. 1 – Basilica di San Giovanni in Laterano, Roma. Extensive research by Prof. Paolo Liverani (Florence University) has enriched our understanding of the complex, but a major collaborative project is required to interpret the remains unearthed by previous excavators. The earliest recorded excavations took place in 1730, the deepest lie 5.5 m below ground level. The Lateran Project is undertaking an intensive scientific survey of the entire structure to integrate information from standing buildings, excavated structures and sub-surface features through the collaboration of Newcastle University (UK), Florence University (Italy), the Institute for Technologies Applied to Cultural Heritage (ITABC-CNR, Italy) and the Direction of Musei Vaticani. Research design. The Lateran Project aims to undertake a fully integrated 3D survey of the excavations under San Giovanni in Laterano. A particular concern is to find an approach that will not only allow collaboration between researchers using a range of established and innovative methods, but also a method that allows an integrated approach to the three-levels of structural data that form the complex (Gaffney et al., 2008). There are the standing features on the modern city surface, as seen in Fig. 1. These can only be fully understood in relation to subsurface features and vice versa. There are also the extensive and inter-cut structures that form the opened area of excavations. Finally, there are the unexcavated deposits that lay either beyond the immediate confines of the site or beneath the area opened to date. Ground penetrating radar (GPR) was used to map standing and sub-surface structures. The aim of these surveys is to identify Roman and high-medieval age remains which could enhance understanding of the ancient topography and the urban evolution of the studied area. The main goals of this survey are the following: 1. to determine the limits of Castra Nova Equitum Singularium , the barracks of the imperial horse guards established by the emperor Septimius Severus; 2. to locate the remains of the buildings of the Lateran Patriarchy. These are known from renaissance plans but up until now it has not proven possible to locate them all on the ground; 3. to determine the full plan of the Santa Croce oratory, built by Pope Ilaro (V century) and destroyed by Sixtus the Fifth; part of this building has been identified by Olof Brandt within the excavated area adjacent to the Baptistery; 4. to determine the full extent of the palatial housing found below the western part of the Basilica. Ground penetrating radar. Data acquisition. For The measurements a GPR SIR3000 (GSSI), equipped with a 400 MHz (GSSI) bistatic antenna with constant offset and a 70 MHz (Subecho Radar) monostatic antenna were employed. Some signal processing and representation techniques have been used for data elaboration and interpretation. GPR surveys were performed, employing theSIR3000 (GSSI) to survey the selected areas outside the Basilica in the S. Giovanni in Laterano square, in front of the Basilica and inside in few internal parts. The horizontal spacing between parallel profiles at the site was 0.50 m , employing the two antennas. Radar reflections along the transepts were recorded continuously, with different length, across the ground at 40 scan s -1 ; horizontal stacking was set to 3 scans. In the area outside the Basilica a total of 777 adjacent profiles across the