This is the first volume in a new series of Hypogean Archaeology aiming to promote the archaeological, architectonical, speleological and historical investigation of artificial cavities. This volume covers the first 55 index cards relating to the underground works registered in the Italian regions of Lombardy, Piedmont and Tusacany. Intended as an initial contribution to the classification and knowledge of artifical cavities, the cadastre includes a "Classification of artificial cavities by typology," essential for an understanding of the vast range of underground cavities.

The study and registration of artificial cavities means the documentation of underground structures. Just as Man started creating buildings on the surface of the Earth, over the course of time, he also perforated the surface thus creating new spaces and handing down structures which are essentially intact, which can be studied, restored and even utilised. In fact there exists an underground heritage, consisting of structures both built and buried underground over the passing of time. The interpretation and understanding of such structures is a source of interesting information on our past, in favour of the present. This series was created under the aegis of the Federazione Nazionale Cavita Artificiali (F.N.C.A.). The aim is to create a base for the disclosure of relevant, scientific research studies, whether monographs, the works of various authors or documentation from conferences and conventions and a series of easily consultable tools for the development of artificial cavity research."

Between 1988 and 2000 a pot-holing project undertook an underground survey of the city of Tarquinia in Italy. This report comprises a catalogue of the man-made cavities that it found along with a discussion of methodology and an analysis of its findings from the Etruscan, Roman and medieval periods. The different types of man-made cavities included caves and mines, structures for conducting, holding, storing and conserving water, those for the disposal of water or sewerage, and those serving religious (crypts, catacombs etc), civil and military functions.