600-year-old mystery solved: Leonardo da Vinci’s secret tunnels discovered in Italy

A team at the Polytechnic University of Milan uncovered secret tunnels beneath Sforza Castle, potentially linked to Leonardo da Vinci's designs.

Scientists have uncovered hidden structures underneath an Italian castle that they believe could be underground passageways which were based on a sketch made by Leonardo da Vinci in 1495, CNN reported. The Italian painter, scientist and architect is believed to have sketched the tunnels for soldiers to secure a quick evacuation if the castle’s defenses were breached.

Leonardo da Vinci spent time at the castle during the late 1400s as a member of the court of Duke Ludovico Sforza. (Representational)

The Politecnico di Milano or The Polytechnic University of Milan conducted various non-destructuve surveys from 2021 to 2023 to digitize the 15th century Sforza Castle’s underground structures using ground-penetrating radar and laser scanning.

“Our findings serve as yet another reminder of how deeply embedded history is within our cities. Only through awareness of this fact, combined with a thorough understanding of history and architecture, can we truly appreciate the importance of preserving and enhancing our cultural and architectural heritage," Francesca Biolo, a research fellow, whose doctoral thesis started the surveys told CNN.

Leonardo da Vinci as a military architect

It is known that the Italian polymath spent time at the castle during the late 1400s as a member of the court of Duke Ludovico Sforza. The duke had commissioned the artist for a painting and during this time, da Vinci created the drawings of defensive structures that closely resemble the layout of the Sforza Castle.

“It is always important to be able to reconstruct the past as precisely and as firmly as possible. In the case of Leonardo, we know that most of his drawings, especially the architectural drawings, were ‘mental’ exercises, ideas for innovative buildings, but that they were not meant as blueprint for actual construction, just ideas of innovative building: paper architecture that existed only as drawings on paper, one might say," Dr. Francesca Fiorani, a Leonardo da Vinci expert told CNN.

Secret tunnels under a castle

When Biolo and her team were working to digitise a well-known underground passageway along the perimeter of the castle they discovered a second secret tunnel which that only been hypothesized by experts for years.

Running parallel to the first tunnel, the second passageway was built three feet beneath the surface and could have been used as a concealed route by soldiers to defend against enemy forces, Biolo said.

The scientists suspect more subsurface structures are lying hidden under the castle but it is difficult to map them as the Sforza Castle used to be six times the size of what it is today. Several demolitions and restorations took place during the Napoleonic wars and at the end of the 19th century leaving the property completely transformed.