For centuries, scholars have debated the true inspiration behind the most famous half-smile in history. Lisa Gherardini del Giocondo, a wealthy silk merchant's wife and the mother of five children, has been a leading contender since an art historian identified her as the sitter in 1550. The 2005 discovery of a 500-year-old note by an acquaintance of da Vinci, which states that the artist was working on Lisa's portrait, confirmed the theory for many scholars.

The Battle of Anghiari (1505) is a lost painting by Leonardo da Vinci, which some critics believe still exists, hidden beneath one of the later frescoes in the Salone dei Cinquecento (Hall of the Five Hundred) in the Palazzo Vecchio, Florence. Its central scene depicted four men on raging war horses engaged in a battle for possession of a standard, at the Battle of Anghiari in 1440.

In 2010, Galitzia deciphered a "mathematical and astrological" puzzle she believes to be hidden in da Vinci's famous painting. According to her translation, da Vinci's hidden message predicts an apocalyptic flood that will sweep the globe from March 21 to November 1, 4006.

In the early morning of August 21, 1911, the Mona Lisa was stolen from its glass case at the Louvre. The police suspected the modernist enemies of traditional art might be involved. Pablo Picasso was arrested and questioned along with avant-garde poet and playwright Guillaume Apollinaire. Both were later cleared and released.

Leonardo's Horse was commissioned in 1482 by Duke of Milan Ludovico il Moro. It was intended to be the largest equestrian statue in the world, a monument to the duke's father Francesco Sforza. Leonardo toiled for nearly 17 years on the plans and a clay model, and seventy tons of bronze were collected by Ludovico for casting the 26-foot statue, but French forces invaded Milan in 1499 and used the clay model for target practice.

The subject matter of Annunciation is drawn from Luke 1:26-39. It depicts the angel Gabriel, sent by God to announce to the virgin Mary that she will miraculously conceive and give birth to a son, Jesus, who will be called "the Son of God". The painting was begun by Andrea del Verrocchio who used lead-based paint and heavy brush strokes. He left a note for da Vinci, one of this students, to finish the background and the angel. Leonardo used light brush strokes and no lead. When the Annunciation was x-rayed, Verrocchio's work was evident while Leonardo's angel was invisible.

If you study the Mona Lisa's left elbow, you may detect a bit of chipped paint left when a young Bolivian chucked a rock at the portrait in 1956. A few months earlier, another assailant had pitched acid at the painting, which hit the lower section. These attacks inspired the bulletproof glass, which in 2009 successfully rebuffed a ceramic mug hurled by an angry Russian woman who'd been denied French citizenship.

The Vitruvian Man depicts a man in two superimposed positions with his arms and legs apart and inscribed in a circle and square. The drawing represents da Vinci's concept of the ideal human body proportions. It is accompanied by notes based on the work of the Roman architect Vitruvius, who determined that the ideal body should be eight heads high.

Salvator Mundi depicts Jesus in Renaissance dress, making the sign of the cross with his right hand, while holding a transparent, non-refracting crystal orb in his left, signaling his role as Salvator Mundi (Latin for 'Savior of the World') and representing the 'celestial sphere' of the heavens. Although some critics believe da Vinci only contributed certain elements of the painting, it sold at auction for $450.3 million in 2017.

Leonardo's Codex Hammer, also called the Codex Leicester, was purchased by Microsoft co-founder Bill Gates in 1994 for $30.8 million. The 72-page notebook, written between 1506 and 1510, contains scientific musings on everything from the reasons why the sky is blue to the luminosity of the Moon to how the movement of water works and how fossils originated.