Monitoring and 3D surveys for the safety fruition of a hypogeum site

The metropolitan area of Napoli (Italy) is characterized by a subsoil rich in cavities and tunnels, initially born as material quarries present in all architectural contexts of Campania. The cavities were reused in later times for different purposes: mainly funeral and burial activities since the Hellenistic revival during the Roman period and later during the Christian era although, in the latter case, the catacombs were even used as place for worshipping functions. Religious activities were not the only reuse for these underground cavities as they were used as aqueducts and tunnels. This underground network of tunnels and cavities includes the numerous archaeological quarries and constitute a patrimony to preserve and enhance. The current use of the Naples underground is cultural tourism, which involves a very high annual passage of visitors in environments that need maximum structural safety. And essential, in order to ensure the safety fruition of the site, assess their stability conditions. In this paper we report the multidisciplinary investigations carried out on an ancient tuff quarry, known as Cimitero delle Fontanelle, in Napoli. In detail the result of diagnostic surveys, geological and geotechnical investigations, and the set-up of monitoring system in order to plan scheduled maintenance were discussed, starting from the previous works carried out in order to design the remedial measure necessary to reopen the tourist site in safety.