image: Ground-penetrating radar reveals new secrets under Milan's Sforza Castle
Credit: Politecnico di Milano
Milan, 14 January 2025 – In the context of a PhD thesis, the Politecnico di Milano carried out a cutting-edge technological investigation, working in collaboration with the Sforza Castle and with technical support from Codevintec. The survey revealed the presence of numerous passages under the Castle, in the area once covered by the "Ghirlanda" or outer wall, some of which could be linked to secret military passages, also shown in Leonardo's designs. According to historical sources, Ludovico il Moro had an underground passageway built to allow him to visit his beloved wife Beatrice d 'Este, who was buried in the Basilica of Santa Maria delle Grazie. This passageway is immortalised in Leonardo's drawings, and has long been the subject of legends and considerable speculation. But now, thanks to technology, it seems that its existence can be confirmed. However, there are many other secret passageways.
The investigation used advanced technologies, such as GPR and laser scanners, to create an accurate map of the Castle's sub-surface and the underground structures. These instruments were able to reveal underground cavities and passageways about a foot or two beneath the surface. As Franco Guzzetti, professor of Geomatics at the Politecnico di Milano, explained: "The aim is to create a digital twin of the Sforza Castle, a digital model that not only shows the current appearance of the Castle, but also allows us to explore the past, by revealing ancient structures that are no longer visible."
As well as providing a historical record, the data collected could be integrated with augmented reality to develop immersive experience projects that combine history and innovation. Francesca Biolo, researcher at the ABC Department of the Politecnico, also pointed out: "The GDR technology has added to our 3D model by providing data about well-known but inaccessible spaces, revealing unknown pathways and suggesting ideas for further research into these secret passages."