Da Vinci's masterpieces: A closer look

Perhaps the only Leonardo da Vinci work in private ownership, it was auctioned by Christie's in New York in 2017 for a record-breaking $450 million. Created around the year 1500, it's one of less than 20 surviving paintings by the master — though its authenticity is still up for debate. In 1958, the artwork changed hands for $60, under the belief that it wasn't an original work.

Leonardo's most famous painting was created when the Italian Renaissance was at its peak. Today, it hangs in the Louvre, in Paris. The year of its completion is as unclear as the true identity of the model. The Florentine Lisa del Giocondo, wife of the cloth and silk merchant Francesco di Bartolomeo di Zanobi del Giocondo, is considered a leading candidate. But many art historians remain doubtful.

This portrait of John the Baptist, who recognized Jesus as the Messiah in the New Testament and spread the word of his arrival, also hangs in the Louvre. His cheerful gaze is an expression of his knowledge. Between 1513 and 1515, Leonardo was in the service of the Vatican. Presumably, Pope Leo X commissioned the painting, which is believed to be Leonardo's last.

Beyond the "Mona Lisa," the true masterpiece of da Vinci's oeuvre is the "Last Supper" found in the Dominican Convent of Santa Maria delle Grazie in Milan. It has been restored several times because the fresco-secco wall-painting technique popular in the late 15th century is not as durable as frescoes painted on wet lime plaster. The artwork is listed as UNESCO World Heritage.

The original no longer exists; instead, there are two copies painted by da Vinci's students. One of the copies is part of a private collection in New York, the other was stolen from Drumlanrig Castle in Scotland in 2003, only to reappear four years later through a raid. Today, the painting with an estimated worth of €40 million ($45.7 million) hangs in the Scottish National Gallery.

Concern over authenticity is a given with artworks that are 500 years old. Experts are unsure about the self-portrait (above), a sketch owned by the Royal Library of Turin. It presumably shows the master himself, but some experts believe the red chalk drawing could have been made long after da Vinci's death. Would da Vinci smirk at the uncertainty?

The Renaissance Man was much more interested in sciences than painting. Da Vinci sketched ideas and observations in architecture, biology, technology and anatomy. The above aerial screw, the Helix Pteron, brings to paper the concept of a flying machine, a precursor of a helicopter. It was never built because he lacked the materials.

Presumably, his inventive talent was one of the reasons there are so few da Vinci paintings — he simply didn't get around to it that often. This drawing is based on the work of the architect Vitruvius, a depiction of a man with ideal proportions, a symbol of symmetry, beauty and body awareness. Most Germans carry the image in their wallet — imprinted on their health insurance card.