New discoveries at the Castello Sforzesco in Milan. An integrated approach through 3D modelling and GPR survey

The research on Castello Sforzesco in Milan developed an integrated 3D information model combining historical sources and contemporary survey technologies. A digital twin was structured through multiple layers of geometric data, organized by attributes and accuracy of the original information. The model quickly proved useful in analyzing theories on hidden underground routes. This potential led to collaboration between the Politecnico and Codevintec Italiana s.r.l., resulting in a wide survey with stepped frequency ground-penetrating radar. The data revealed numerous original structures and others only hypothesized. One example is the second counterscarp gallery, drawn by Leonardo da Vinci and now located a few centimeters from the currently accessible one. Other results suggest the debated gallery leading to Santa Maria delle Grazie. The study shows how integrating historical analysis with conventional and modern survey techniques, enriched by geophysical investigations, can yield valuable insights and enhance understanding of architectural heritage.