Leonardo da Vinci’s Mona Lisa — one of the most famous paintings in the world — is shrouded in mystery; from questions around the figures identity, to her puzzling, enigmatic expression. Now, at least one of the artwork’s secrets has been revealed, according to a geologist based in Italy.

Ann Pizzorusso, who is both a geologist and an art historian specializing in Leonardo and the Renaissance era, believes she has deduced the location of the Mona Lisa using her geological expertise.

Three decades ago, Pizzorusso visited the town of Lecco on the southeastern shore of Lake Como in Italy — where she believes the painting is set — to retrace Leonardo’s steps, armed with diary entries and drawings from the artist. “In his notebook he mentions being in Lecco,” she told CNN in a phone interview. “He was working as an engineer.”

According to Pizzorusso, the project Leonardo was working on was canceled, but his geological field sketches remained (one red chalk drawing of a mountain range near Lecco belongs to the Royal Collection at Windsor, London).

While Pizzorusso is not the first to have theorized on the location of the Mona Lisa (in 2011, an art historian attributed the painting’s scenery to a small town called Bobbio, while another to Arezzo) she believes she is the first geologist.

Previous calculations have concentrated on the arched bridge over the Mona Lisa’s right shoulder. However, Pizzorusso insists more can be gleaned from the unique rock formation in the horizon. “Bridges are fungible,” she said. “If you look in the background, you’ll see pinnacles. It’s a type of erosion that happens in limestone that has fractures in it and breaks off in blocks, almost like a sawtooth pattern… We can show limestone exists in (Lecco). When you look at the Mona Lisa, there’s a series of mountains in the background that have this sawtooth pattern.”

Similarly, the body of water behind Mona Lisa is geologically specific, believed by Pizzorusso to be Lake Como — a subalpine glacial lake dating back around 10,000 years. “If you look behind her you have the elongated glacial lakes that have a particular form like fingers,” she said. “Because when the glacier moved it scoured out certain pieces of land.”

Despite her confidence, Pizzorusso kept her inkling quiet for 30 years, telling only other Leonardo scholars in casual conversation. She returned to Lecco this week, still assured that “everything added up,” and will now present her findings at a geology conference in the town.

While the pairing of earth science and art history may seem disparate, Pizzorusso argues the interdisciplinary approach can enrich the viewing experience of Leonardo’s work. “Botticelli, even Michelangelo did terrible backgrounds because they felt the figures were more important,” she told CNN. “If the background is painted right, it gives you more of an appreciation for nature.” Though Pizzorusso admits she is surprised at the widespread interest. “Maybe (Leonardo) was trying to channel me for the environmental movement or something,” she joked. “It’s a testament to how much people love this painting.”

But the discovery may only lead to more mystery. If the location is Lecco, as Pizzorusso suggests, more questions remain as to why the renowned painter chose that particular spot, for this particular portrait.

“We don’t know who (Mona Lisa) is, some believe she was a rich Tuscan merchant’s wife,” she said, referring to a popular historical theory that proposes the figure was based on Italian noblewoman Lisa Gherardini. “Why did he put her in this wild, untamed environment? This is not Tuscany. What was he trying to tell us by putting this serene, enigmatic lady in this rugged, alpine environment?” Said Pizzorusso.

“I’m really intrigued as to what his message was to us.”