Historians and art experts already know a lot about the most famous painting in the world: Leonardo da Vinci’s Mona Lisa. Each feature, each color of the portrait has been carefully studied and analyzed for years. But now an Italian historian claims to have identified a detail depicted in the background of the iconic portrait that has been stirring debate for decades, reports the Guardian.

Italian historian Silvano Vinceti said he had no doubt that the Romito di Laterina bridge in the province of Arezzo was what Leonardo da Vinci painted in the countryside landscape behind the enigmatic Mona Lisa. The bridge in question is on the right side of the portrait, just above the woman’s shoulder.

For years, several theories have identified the bridge as Ponte Buriano and Ponte Bobbio in the Italian town of Pacenza. Silvano Vinceti came to this conclusion after studying historical documents and drone footage. He even carried out comparative studies between the painting and photographs of the region.

The latter notably highlighted the number of arches represented on the painting, four in this case, which corresponds to the number of arches possessed by the Tuscan bridge. According to the historian, Leonardo da Vinci resided in Valdarno at the time he painted the picture and that the Romito di Laterina bridge, frequently used at the time, was probably used by the painter. Built in the 16th century, the bridge now has only one of the four arches.

The mayor of the village of Laterina, Simona Neri, told the newspaper that the historian’s theory aroused the enthusiasm of the townspeople. “We have to try to protect what’s left of the bridge, which will require funds,” he said. The announcement of this discovery should encourage tourists to come in large numbers to admire the building.