New data from an urban archaeology project on a medieval town site. High-resolution GPR surveys in Piazza delle Carceri, Prato (Florence, Italy).

To enhance the knowledge of the subsoil in the area of Piazza delle Carceri, as to the location and conservation of unknown buried medieval structures, a scientific collaboration between University of Florence (Department SAGAS, University of Florence) and the Institute of Technologies Applied to Cultural Heritage (ITABC-CNR), started in 2012 and it is still in progress. The investigated area has been hypothesized to be characterised by a sequence of complex buildings, related to the medieval period. In this complex site a series of GPR surveys employing different frequencies were carried out. The archaeological surveys, from September 2012 until July 2013, was organized through four different phases characterized by an increasing degree of investigations. The first diagnostic phase based on geophysical survey was followed by the opening of three stratigraphic excavations, to check the results of the GPR prospection (Surveys C, D, E, phase II). Subsequently, the three excavated areas were expanded and new trenches were opened (phases III-IV), to fully document the archaeological potential of the entire square (Vannini et al., 2012-2013).