Written by Delia Gallagher, CNN

A 500-year-old mystery at the Vatican has just been solved. Two paintings by Renaissance master Raphael were discovered during the cleaning and restoration of a room inside the Vatican Museums.

Experts believe they are his last works before an early death, around the age of 37, in 1520: "It's an amazing feeling," said the Vatican's chief restorer for the project, Fabio Piacentini.

"Knowing these were probably the last things he painted, you almost feel the real presence of the maestro."

The two female figures, one depicting Justice and the other Friendship, were painted by Raphael around the year 1519, but he died before he could finish the rest of the room. After his death, other artists finished the wall and Raphael's two paintings were forgotten.

The clues

In 1508, Raphael was commissioned by Pope Julius II to paint the his private apartments. The artist completed three rooms, known today as the "Raphael rooms," with famous frescoes like the School of Athens

He then began plans for the fourth room, the largest in the apartment, a banquet hall called the Hall of Constantine. His plan was to paint the room using oil, rather than the traditional fresco technique.

An ancient book from 1550 by Giorgio Vasari, "Lives of the most excellent painters, sculptors and architects," attests that Raphael began work on two figures in a new experiment with oil. That clue was the key to the discovery. When restorers began to clean the walls of the Hall of Constantine in 2017, they realized two female figures were painted in oil, while the rest of the room was painted using the fresco technique.

Ultra-violet and infrared photos confirmed scholars suspicions: these two paintings were not like the rest, the oil painting clearly showing through in the advanced technology. To the expert eye, it was clearly Raphael for other reasons as well.

The brushwork

Vatican restorer Fabio Piacentini says there is a confidence in the brushwork that is typical of Raphael: "The way the paintbrush moves," Piacentini explains, "even the subtlety of the point of the brushes used to create the small wisps of hair."

Raphael also created unusual shades of color, which began to show through during the cleaning, according to Piacentini. The fact that there is no sign on these two figures of a preparatory drawing underneath, such as a lesser painter might have used, is another sign of the maestro's hand, he says.

A detail of the discovered paintings. Credit: CNN

The head of the Vatican Museums, Barbara Jatta, says restoring the Raphaels and the whole room will take them until at least the year 2022: "It's one of the most important projects of the last decades - apart from the Sistine Chapel -- done in the Vatican Museums," she says.

Although it is unlikely that there are other hidden masterpieces on the walls of the Vatican, the Museum's restorers and scholars always keep their eyes open: "That's the beautiful thing of different projects," Jatta says. "We are still searching...it never ends."

The bill

The restoration of the two re-discovered Raphaels and the rest of the Hall of Constantine at the Vatican will take until 2022 to complete and cost 2.7 million euros -- around $3.1 million.

Much of that expense, so far, has been covered by the New York chapter of the Vatican's Patrons of the Art , says Vatican Museum Director, Barbara Jatta. The Patrons are a special group of donors, mainly from the United States, but also Europe and increasingly from Asia, who support art restoration at the Vatican.

"We produce a wish book every year," says Barbara Jatta, "that means important projects that are going on; we share ideas with them."

Individuals can become patrons of Vatican art for a $600 annual membership fee. They can then adopt special restoration projects from the Vatican Museums Wishbook and contribute to the restoration and safekeeping of the Vatican's -- and the world's -- art patrimony.

Watch the video above to find out more about the discovery