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.