3D GPR survey for the archaeological characterization of the ancient Messapian necropolis in Lecce, South Italy G. Leucci ⁎, L. De Giorgi, G. Di Giacomo, I. Ditaranto, I. Miccoli, G. Scardozzi Consiglio Nazionale delle Ricerche, Istituto per i Beni Archeologici e Monumentali, Lecce, Italy abstract article info Article history: Received 11 January 2016 Received in revised form 11 May 2016 Accepted 12 May 2016 Available online xxxx Extensive urbanization may cover important archaeological structures that are still buried in urban areas, and Ground Penetrating Radar is one of the most reliable geophysical technique for resolving buried archaeological structures in urban territories. In this paper a case study that involves a geophysical survey employing the surface three-dimensional (3D) GPR techniques, to characterize the investigated areas from the archaeological point of view, is illustrated. GPR measurements, integrated with archaeological and topographical information aimed at the production of a digital archaeological map integrated in a webGIS platform, were carried out in some areas at the historical centre of Lecce (Apulia, Italy). The investigated areas are related to some sectors of the Messapian necropolises (dated mainly in 4th–3rd century BCE), characterized by different types of graves (pits dug in the bedrock or built with slabs, sarcophagi and hypogea) that lying also inside the settlement surrounded by city walls. The survey was carried out using the IDS Hi Mod georadar system, incorporating a dual band 200– 600 MHz centre frequency antennae. The GPR time slices were constructed from closely spaced parallel profiles. The time slices, computed from averaging radar reflections over vertical time windows several nanoseconds thick, are used to map subsoil features associated with its structure. The time slices were georeferenced in the ar- chaeological map of Lecce in order to acquire new data on the distribution and the ancient topography of the fu- nerary areas inside the settlements. Moreover, to facilitate the interpretation of the results, a three-dimensional image was constructed using closely spaced parallel profiles, which are interpolated. © 2016 Elsevier Ltd. All rights reserved. Keywords: GPR Archaeological map webGIS Messapian tombs 1. Introduction Ground-penetrating radar (GPR) techniques are relevant to land- scape reconstruction in an archaeological context. GPR is a fast and cost-effective electromagnetic (EM) method, which in favorable condi- tions, i.e. mainly resistive non-magnetic environments, can provide valuable information on the shallow subsurface. As it is based on the propagation and reflection of EM waves, it is sensitive to variations of the EM parameters in the subsoil, especially the dielectric constant and the electric conductivity (Davis and Annan, 1989). The archaeolog- ical community has also recently seen the need for near-surface mapping using GPR in order to identify buried cultural remains for pro- tection and future preservation and as a planning tool for selective exca- vation, that is a very important prerequisite when, as in this case, the context of the study is an urban centre inhabited without interruption from antiquity. In this paper, the results of a GPR survey carried out in 2013–2014 over three areas, located in the city centre of Lecce (Fig. 1), are reported. The site of the historical centre of Lecce was inhabited at least from the Iron age (9th–8th century BCE) (D'Andria, 1995). In the Messapian age (7th–3th century BCE), Lecce is characterized by a scattered settlement, with inhabited areas alternating with open spaces, public areas, necropolis and places of worship. During the 4th century BCE, Lecce is transformed into an urban-type set- tlement, even with the construction of city walls at the end of the same century, which enclosed a surface of about 60 ha. The most significant archaeological remains for this period is constituted precisely by powerful sections of city wall and numerous tombs with their grave goods. In the 3rd century BCE Lecce was conquered by Romans and after the Social war the city, named Lupiae, became a municipium as- cribed to the Camilia tribe (Giardino et al., 2000; Giardino, 2008). During the Late Republic age and the Early Imperial times the settlement was reorganized and the easternmost sector, previously occupied by a Messapian necropolis, was monumentalized by the construction of the main public building, such as the amphitheatre, the theatre, the baths, lo- cated at short distance from each other (Giardino et al., 2000; Giardino, 2008; Giardino, 1994; Giardino and Lonoce, 2011). Only few sectors of the first two monuments are nowadays visible (Fig. 1), partly brought to light by the demolition of some buildings in Journal of Archaeological Science: Reports 7 (2016) 290–302 ⁎ Corresponding author. E-mail address: g.leucci@ibam.cnr.it (G. Leucci). http://dx.doi.org/10.1016/j.jasrep.2016.05.027 2352-409X/© 2016 Elsevier Ltd. All rights reserved. Contents lists available at ScienceDirect Journal of Archaeological Science: Reports journal homepage: www.elsevier.com/locate/jasrep