In Campania (southern Italy), the widespread presence of anthropogenic cavities in the subsoil of the Neapolitan and Caserta provinces is well known. In these towns, the underground quarrying activities were performed for centuries to extract volcanic tuffs for buildings. The urban developments have sealed many signals of the presence of cavities and their real extent is almost unknown, thus representing a geological hazard and contributing to the subsoil instability of many places. This contribution will show the main cavity typologies recognized across an area north of Naples according to the geological characteristics of the subsoil. The main aim of the study is the cataloging of the cavities and the analysis of the city subsoil as their presence may easily trigger the collapse of the shallow or deeper soils. Moreover, the recognition and sustainable reuse of cavities contributes to enhancing the cultural and touristic promotion of a territory. In this study, a database framework was elaborated that includes all the possible architectural, geological and geotechnical elements of the cavities. Data were managed in a GIS environment in order to provide a useful tool for monitoring and managing the cavities for risk mitigation and tourism enhancement.

The case study of the monumental complex of San Francesco le Moniche, built in the ancient Norman county Aversa, in northern Campania (Italy), is analyzed here. The cultural heritage of the complex and the additional value associated with geoheritage (building stones and underground extraction cavities) have been highlighted. The building stratification of the complex was reconstructed based on documentary sources, including historical cartography and photographic documentation of postcards from the early 1900s. It began around 1200 and ended in the 20th century; part of the original citadel was dismantled and incorporated into the urban fabric in the Fascist era. The building stratification of the complex was also read from the distribution and architecture of the existing underground cavities from which the building stones were extracted. The subsoil, reconstructed on the basis of geological and geophysical data, is made up of a tuff substrate, starting from approximately 5–6 m from the ground level, which represents the main building stone as well as being an important testimony to the long volcanological history of northern Campania. Laser scanner surveys of the known and accessible cavities were carried out to obtain a three-dimensional view of the entire monumental complex and its underground spaces. The results provide a clear example of a geoheritage–cultural heritage interface which reminds us of the importance of an integrated approach in their valorization, specifically in urban areas. Additionally, the results of the study allowed us to improve the knowledge of the complex and the site, and provide useful tools for the planning of future targeted investigations.

In northern Campania (Southern Italy), the historic center of many towns is characterized by the widespread presence of cavities in the subsoil, excavated over the centuries for quarrying tuff blocks for buildings, along with cathedrals, churches and chapels. A singular feature of these places of worship is, in fact, the presence of a wide and frequently connected network of underground cavities and tunnels, which were used for hydraulic, religious or connecting purposes. The cavity network is often unknown, abandoned or even buried, thus representing a risk for their susceptibility to sinkholes. Such elements are important as cultural heritage of inestimable value and as attractors for tourism; for this reason, the multidisciplinary study conducted on a place of worship in the Caserta area is illustrated herein: the Cloister of Sant’Agostino, in Caserta (XVI century CE). A geological and geotechnical characterization of the subsoil was performed at first. A laser scanner survey of the accessible cavities and the external churchyard was carried out. The resulting 3D model of the underground sector allowed for a clear understanding of the room size, their location, the levels and the path of the corridors. To understand the extension and layout of the crypts, Electrical Resistivity Tomography (ERT) surveys were undertaken in the surrounding areas. The analysis of the ERT measurements revealed some anomalies that could be ascribed to unknown structures (crypts). Finally, numerical methods were applied to estimate the stress state of the soft rocks and the potential areas of crisis, with preliminary assessments of the influence of the presence of cavities on the stability of the subsoil. The results allowed us to improve the knowledge of the study site and provide useful data for the planning of future targeted investigations, underlining how integrated research between applied disciplines can provide indispensable support both in the management and mitigation of geological risks in urban areas and in the sustainable reuse of hypogea.

Relationships between geoheritage and cultural heritage are increasingly becoming a topic of study, especially in urban contexts. Their integrated reading adds value for educational and urban geotourism purpose, being the latter an emerging sector of sustainable tourism. The case study of the monumental complex of San Francesco le Moniche, built in the ancient Norman county Aversa, in the northern Campania (Italy), is analyzed here. The cultural heritage of the monumental complex and the additional value associated with the natural heritage (geological and geomorphological context, building stones) have been linked. The building stratification of the complex has been read not only from documentary sources, but also from the distribution and architecture of the existing underground cavities, the building stones, from ancient images and even postcards, integrating disciplines such as geosciences, architecture, archaeology, speleology, engineering. The results provide a clear example of a geoheritage-cultural heritage interface and the importance of an integrated approach in the valorization of the cultural and natural heritage of urban areas. The results allowed us to improve the knowledge of the study site and provide useful tools for the planning of future targeted investigations.