The seminar focused on underground environments, both natural and artificial, as a collective heritage of inestimable value, combining material and immaterial elements, history and nature, culture and technology.

Since prehistoric times, caves have been places of refuge, shelter, worship and burial. In them, mankind’s earliest artistic expressions testify to a deep connection with spirituality, the mystery of life and the afterlife. But the subterranean world is not confined to natural cavities: out of necessity and ingenuity, man has shaped the subsoil, digging quarries, mines, hydraulic canals and military shelters. Many of these once vital structures have been abandoned and their study is now of vital importance in archaeology, history, anthropology, town planning and architecture.

These environments present considerable exploration challenges: their irregular geometry, lack of conventional landmarks, requires the use of advanced speleological techniques for surveying and documentation. Furthermore, caves and underground structures are fragile ecosystems, suspended between nature and human intervention. Their ecological balance can be altered by excessive use or the effects of climate change. Therefore, their protection requires a sustainable approach supported by the latest digital technologies.

In this scenario, the Digital Twin (DT) concept emerges as an innovative solution for the management and conservation of underground heritage. The Digital Twin is a virtual replica of a physical entity, capable of simulating scenarios and predicting the impact of interventions before they are carried out. Applied to underground environments, the DT provides a dynamic and integrated view of the state of a site, optimising protection and enhancement strategies.

The seminar highlighted the difficulties and critical issues involved in implementing digital twins for complex structures and underground environments. A DT consists of three essential elements

• The physical twin: the real site, i.e. the cultural heritage to be protected.
• The Digital Twin: its virtual representation, which faithfully reproduces its characteristics.
• The Linking Mechanism: the flow of data between the Physical Twin and the Digital Twin, which makes it possible to simulate interventions and predict their effects in real time.

But what aspects of a hypogeal environment must be included in a digital model? Which parameters are crucial to faithfully reproduce such a complex ecosystem? And above all, how can a DT contribute to the conservation and sustainable management of these extraordinary places?

During the seminar, experts in the field addressed these questions and demonstrated how advanced surveying technologies, from photogrammetry to laser scanning, make it possible to obtain detailed data on the morphology and state of conservation of underground environments. They proposed innovative systems for data segmentation and semantic enrichment, developed new diagnostic and intervention methods, and demonstrated the integration of data collected by sensors placed on physical artefacts into digital geometric models. This approach makes it possible to monitor environmental conditions in real time, to assess conservation strategies in a predictive way, and to optimise both interventions and site accessibility.

The digitisation of underground heritage is a complex challenge that requires a multidisciplinary approach capable of combining technological innovation and scientific research. Only through conscious and sustainable management will it be possible to preserve these unique environments, the silent guardians of our history, for future generations.