Unveiled on August 19th 1960, the giant statue of Leonardo da Vinci at Rome’s Fiumicino-Leonardo da Vinci Airport has greeted visitors ever since. Millions and millions of people have passed it over the decades, but it was not until 2006 that a secret hidden inside the statue was discovered.

The monumental bronze statue with marble base is the work of the Bulgarian artist Assen Peikov, who expatriated to Italy during World War II. When the city of Rome announced a competition for a work of art to be installed at Fiumicino Airport, Peikov won, and the resulting 60-foot statue of the Renaissance giant holding his famous “aerial screw” design would become the sculptor’s largest and best-known work.

In 2006, the statue needed renovation. During the course of this work, one of the workers made a strange discovery: a small hatch, located at a height of about 30 feet, approximately in the middle of the statue. The hatch was carefully opened and inside were found two parchments, still in perfect condition.

One of the parchments, written in classical Latin, tells the history of the area where the airport now stands, going back to ancient times and including descriptions of the landscape that predated human development. The other parchment provided a list of the people who attended the unveiling, mentioning (among others) Giovanni Gronchi (President of the Italian Republic in 1960), and Giulio Andreotti (Minister of Defence in 1960 who would go on to become Prime Minister).

It is assumed that the hatch and parchments were the work of Peikov, but whether that is true—and if it is, why he did it—remains unknown, as he passed away in 1973. Independent work is being done to verify the information contained in the parchments.

Even if the secret of the statue is not widely known, sometimes people can be seen looking the statue up and down with binoculars, much to the amusement of passersby unaware that these peculiar characters are trying to spot the mysterious hatch.