Researchers from the Polytechnic University of Milan have uncovered underground tunnels at Sforza Castle (Castello Sforzesco) in Milan using ground-penetrating radar and laser scanners. The existence of these tunnels was previously mentioned in the works of Leonardo da Vinci, according to the university's website.
Built in the 15th century, Sforza Castle has long been a focal point for scholars and historians. It has served various roles over the years, including that of a residence, fortress, and center of power in Milan. The castle is surrounded by numerous mysteries, some of which have now been confirmed. A legend suggested that a vast network of secret passages existed beneath the castle, as described by da Vinci. Modern technology has now validated the existence of these tunnels.
The study employed advanced technologies, including ground-penetrating radar and laser scanners, which allowed researchers to detect voids and underground passages just below the surface.
Professor Franco Guzzetti from the Polytechnic University of Milan stated that the project's aim is to create a 'digital twin' of the castle. This model will facilitate the study of hidden elements of the castle that were previously inaccessible.
Researchers believe that some of the discovered tunnels were used for military purposes. Additionally, one of the tunnels may have been connected to a church where Duke Ludovico Sforza mourned his wife, Beatrice d'Este. It is said that the duke never recovered from the loss, leading to what historian Luciano Chiappini described as 'almost insane mourning,' ultimately resulting in the decline of the Sforza dynasty.
Sforza Castle also inspired architect Aristotele Fioravanti in the construction of new fortress walls for the Kremlin in the 1470s and 1480s, particularly evident in the recognizable 'swallowtail' crenellations on the Kremlin walls.
In August 2024, Milan's city authorities announced the commencement of restoration work on Leonardo da Vinci's frescoes in the castle. The work is scheduled to begin in early 2025 and is expected to be completed by the start of the 2026 Winter Olympics, which will take place in Milan and Cortina d'Ampezzo. The project is budgeted at €1.625 million.
Previously, archaeologists used ground-penetrating radar and acoustic surveys to discover a hidden network of tunnels, known as Chincana, extending over 1.75 km in Cusco, Peru. This network includes three branches: one leading to Callispukio, another to the Muyucmarca tower in the Sacsayhuamán fortress, and a third running behind the San Cristobal church. Key information about the tunnel layout was obtained from records made in 1594 by a Jesuit whose name has not survived.