Renaissance master Leonardo da Vinci painted a fresco called "The Battle of Anghiari" that has been lost for more than five centuries. It appears it could have been hidden in plain sight.

A team of art researchers and scientists believe they have found the missing painting--behind a wall in the city hall in Florence, Italy, reports Reuters.

And it's not just behind any old wall. It's behind a wall that is covered in a painting by Giorgio Vasari. A tantalizing clue is on the Vasari fresco: "Cerca Trova" is painted on it, which means "Seek and you shall find."

The photo above shows part of the Vasari fresco with the words "Cerca Trova."

"Together with art historians and scientists combining historical evidence and technology, this research team has unlocked a mystery that has been with us for more than 500 years," said Terry Garcia, an executive vice president of the U.S. National Geographic Society, which sponsored the research.

Called the "Lost Leonardo," the project is controversial because no one knows for sure that da Vinci's painting is beneath the Vasari. To make the initial determination, researchers had to drill several holes into the existing Vasari fresco.

What do we know about the missing da Vinci painting? It was commissioned by Florence's leaders at the beginning of the 16th century when Leonardo was at the height of his career. They wanted him to paint a massive fresco that celebrated the Florentine Republic's victory over the Milanese in a battle on the plains of Anghiari that took place on June 29, 1440.

But Leonardo loathed war as "a most beastly madness." In the painting, he depicted a group of horses and riders furiously fighting. One year after he started the project, he abandoned it, likely because the experimental technique he was using for frescoes had failed. But some of his preparatory studies remain, as well as other artists' copies of the original fresco, reports Reuters.

Whatever traces of the original remained were lost more than 500 years ago when Giorgio Vasari renovated the great Sala dei Cinquecento in Florence's Palazzo Vecchio. He was instructed to paint a new fresco called the "The Battle of Marciano," to accommodate the higher walls.

Some art historians insist that Vasari was adamant about preserving Leonardo's work, so he built a new wall with an air gap of several centimeters in front of the da Vinci painting to preserve what was left. Others disagree, insisting Vasari destroyed the da Vinci.

By using a tiny, medical-style endoscope and other high-tech tools inserted through existing cracks in the outer wall of the Vasari fresco, researchers were able to take samples of substances underneath.

And what did they find? "We found traces of pigments that appear to be those known to have been used exclusively by Leonardo," Maurizio Seracini, an engineer and expert in art diagnostics, told Reuters. One of the black pigments is believed to be the same type used by Leonardo on the "Mona Lisa."

--From the Editors at Netscape