Once only indicated through a sketch by Leonardo da Vinci from around 1495, concealed passageways have been discovered underneath the Sforza Castle in Milan, Italy.

Researchers in Italy may have uncovered underground tunnels beneath Milan’s Sforza Castle that were once only known through a sketch by Leonardo da Vinci, according to a report by CNN.

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

Researchers have discovered hidden tunnels beneath Milan’s Sforza Castle, which may have been used for military defense, possibly connected to Leonardo da Vinci’s designs. The underground passageways uncovered include a previously unknown tunnel and structures suggesting real-world influence from Da Vinci’s architectural sketches.