The Hypogeum of Calaforno is one of the most intriguing structures of prehistoric Sicily, an underground sequence of 35 chambers preceded by a vestibule and a megalithic entrance, built in the Late Copper Age. The book presents the results of the investigations directed by Pietro Militello on behalf of the University of Catania inside the hypogeum between 2013-2017. In the first section, written by Pietro Militello, a description of the hypogeum is given. Through an architectural, functional and energetics analysis of the inner part of the hypogeum and the results of archaeological soundings, a complex history of use, reuse, abandonment and changes in use (funerary, religious, residential etc.) is reconstructed, spanning almost three millennia. At the same time, the publication of other previously unknown hypogea resituates the Hypogeum from its isolation in Sicilian prehistory. In the second section, written by the members of the research team, a detailed analysis is presented of the geology of the area, and the publication of prehistoric, protohistoric and medieval pottery recovered in the excavations, together with studies on architectural, faunal and anthropological remains. Two final chapters present a preliminary report on the work of the archaeological service of Ragusa in the outdoor area of the Hypogeum and in the wider region.