According to the historian Silvano Vinceti, another detail in the Mona Lisa painting that helped identify the Romito di Laterina bridge was the rock formation behind the sitter’s right shoulder. Vinceti described them as clay pinnacles located ten miles away from the bridge, as presented in the photograph below.

Most likely they are the monumental rocks known as the balze (crags) of Valdarno, “created from sand, clay and gravel, and shaped by the wind and rain in a place where millions of years ago, there was a huge lake…”

Vinceti was not the first to associate these crags on the shoulder of Mona Lisa with those of Valdarno, located between Florence and Arezzo. Other researchers have pointed out the similarity. However, what no-one has yet discovered is that Leonardo embedded in his depiction of the crags a likeness to one of his sketchbook drawings from 1478, the head captioned: ‘Fioravante di Domenico… in Florence is my most cherished companion, as though he were my…’” I presented details about this last month at this link.

To best visualise the feature and make a comparison to the drawing, the painting needs to be rotated 90 degrees to the left. When the painting is rotated 90 degrees to the right then another feature appears, the head of a lion, and representing Leonardo, the other head in the sketch. 

A third figure is also embedded in the crags, its head reminiscent of the Archangel Uriel’s turned head in Leonardo’s Virgin of the Rocks (pictured right), perhaps suggesting the cavernous backdrop in this earlier painting was also inspired by the baize of Valdarno.

Another feature in the Mona Lisa painting is the winding path from the lion’s head. This too is possibly a pointer to one of Leonardo’s first paintings, the unfinished portrayal of Jerome in the Desert which also features a rocky backdrop, and a lion with a winding tail.

But why would Leonardo want to reference in the Mona Lisa painting an earlier drawing of the head of a man made around 1478? And could the faceless ‘Uriel’ and the ‘Mona Lisa’ be connected in some way, or be even the same person?

This is what Leonardo wrote in his notebook on the subject of pareidolia: 

A Way of Development and Arousing the Mind to Various Inventions:
“I cannot forbear to mention among these precepts a new device for study which, although it may seem but trivial and almost ludicrous, is nevertheless extremely useful in arousing the mind to various inventions. And this is, when you look at a wall spotted with stains, or with a mixture of stones, if you have to devise some scene, you may discover a resemblance to various landscapes, beautified with mountains, rivers, rocks, trees, plains, wide valleys and hills in varied arrangement; or again you may see battles and figures in action; or strange faces and costumes, and an endless variety of objects, which you could reduce to complete and well drawn forms. And these appear on such walls confusedly, like the sound of bells in whose jangle you may find any name or word you choose to imagine.”

THE NOTEBOOKS OF LEONARDO DA VINCI, CHAPTER IX, THE PRACTICE OF PAINTING