SOtto Siena (SOS): verso nuovi paradigmi di archeologia urbana

The SOS project (the acronym comes from ‘SOtto Siena’, in English ‘Beneath Siena’), promoted by the Tuscany Region and coordinated by the University of Siena in collaboration with the Superintendency of Archaeology, Fine Arts and Landscape for the Provinces of Siena, Grosseto, and Arezzo (in partnership with the Municipality of Siena, the Regional Museums Directorate of Tuscany, and private companies) stems from the desire to create a useful tool for the knowledge and protection of the archaeological evidence in the urban area of Siena (Italy). Siena constitutes one of Italy’s least known historical centres in its historical and archaeological evolution, despite the fact that numerous archaeological excavations have been carried out but have so far remained almost entirely unpublished. Within this framework we have identified and developed three main lines of action including: the development of a 3D Archaeological WEBGIS of Siena shared by the main partners in charge of the research aimed to the analysis, management and conservation of the urban landscape; the systematic acquisition of Ground Penetrating Radar (GPR) data of all the public spaces in Siena such as streets, squares, courtyards and gardens that are at least theoretically accessible for the mapping of archaeological features and utilities down to a depth of about 2 m and over an estimated 25 hectares of surveyable areaa; finally, the project envisages the retrieval and data entry into the GIS of all the historical-archaeological, geo-pedological knowledge of the city and the interpretations of the GPR surveys. The WEBGIS collects all information regarding historical and archaeological research carried out in Siena, combined with new acquisitions from field activities. The data concerning past research includes the main publications that have dealt with the historical and archaeological evolution of the city, but also dissertations, archival documents, and excavation records that have never been published. GPR data collected so far allowed us to identify several features that we interpreted in particular as underground utilities, archaeological evidence, and a fair amount of elements of uncertain interpretation. In order to improve the interpretation of the GPR data, instead of proceeding in the traditional way and thus reducing the 3D data to 2D (time slice), an important part of the work was devoted to the development of a pipeline for vectorizing the anomalies in 3D. The WEBGIS (SITAS) is a clone of the SITAR (WEBGIS of Rome); however, we developed a new tool for the visualisation of 3D data aimed to visualize GPR datasets. The availability of an already well-tested WEBGIS allow us to focus on the development of a 3D visualization tool that is essential to analyze, interpret and manage the complexity inherent in the radar datum in an urban context characterized by a very articulated morphology and the volumes of the built-up area. The inclusion of the third dimension on such a large scale has never been tested before, and the impact is not limited to knowledge and research but directly affects the analysis of the risk and archaeological potential of the city, and is a useful tool for urban planning and, more generally, for the management of the underground. All archaeological data and interpretations are accessible through the WEB and can be accessed graphically and through the data base containing the records and the attributes associated with each geometry. Like SITAR, SITAS is an innovative, open source and open access information system aimed to the improvement of the knowledge, conservation and enhancement of the archaeological heritage. After two years of activity, we can say that a number of results have been achieved and some trends emerge quite clearly. The SOS project in this first phase clearly demonstrated its potential by implementing an WEBGIS in which the knowledge about the city was collected. The implementation of subsurface GPR scanning required the development of interdisciplinary expertise, protocols, and complex institutional relationships but the results were entirely positive demonstrating clearly the concrete possibility of the project’s implementation and the extraordinary potential of the prospecting method for the knowledge and management of the city’s underground. It is important to point out and be aware that SOS is an experience that is far from over. The project is still in a completely preliminary and extremely delicate stage. In order to continue this experience, it is essential to urge all the institutional and entrepreneurial components of the working group, the territorial authorities (Province and Region), the Ministry of Culture, the Ministry of University and Research, and other institutional partners to support the follow up of this experience, which has among its founding objectives the knowledge and technology transfer to any other historical urban context in Italy as well as abroad.