Rupestrian works and artificial cavities: categories of construction techniques.

Artificial cavities, i.e. man-made structures excavated within rock masses in the mountains, below the ground, or in the subsoil of urban areas, are typically distinguished based upon the epoch of realization and the function for which they were originally used. They can be ranked into the following types, in turn divided in sub-classes: hydraulic works, dwelling works, worship works, war works, mining works, transit way works and others. The above criteria are essential for establishing a general common line aimed at providing optimal elements for cataloguing and comparing subterranean features, which may favor the creation of databases functional to knowledge, protection and enhancement of the hypogean works. In addition, there is another useful aspect for studying the origin and evolution of underground structures that takes into account their implementation modalities. The National Commission on Artificial Cavities of the Italian Speleological Society has identified, according to its experience in the field and in function of the construction techniques, six general categories of underground works: cavities dug in the subsoil, cavities built in the subsoil, cavities obtained by re-cover, anomalous artificial cavities, mixed artificial cavities and natural caves modified by men (anthropized caves). In this contribution we will discuss the specific details of each category, thus extending the concept of rupestrian heritage, usually confined to temples or dwellings carved in the rock, to a culture of building in "negative" that finds larger and more diversified evidences.