All tickets must be booked in advance (they're released four months ahead of time). If you missed out your best chance is to arrive before the first appointment (8.15am) in case there's been a cancellation.
Little remains of the original painting, which started to deteriorate soon after its completion. Da Vinci had experimented with a new method of painting on dry plaster (instead of wet), which was less durable but allowed for greater detail and luminosity.
Da Vinci lived in nearby Casa degli Atellani during the painting of his masterpiece and was given a vineyard on the same grounds. Today you can tour his vineyard, recreated with the help of wine geneticists.
Jesus originally had feet but this portion of the painting was demolished when they added a door to the refectory in 1650.
It was almost destroyed several times, by flood, Allied bombing in WWII, Napoleon's troops who used the room as a stable, and even well-meaning restorers in the 19th century.
Your visit will be short (15 minutes) but you'll have the space to really appreciate the artwork as only 25 people are allowed in at one time.
It took three years to finish. When the prior of the monastery complained about how long it was taking, it's said that Da Vinci responded by threatening to use the prior's face as the model for Judas.
It's famed for its unique perspective. Reputedly Da Vinci hammered a nail into the wall and attached string in orthogonal lines to create this effect.
The Holy Trinity is emphasized through the repetition of the number three. The apostles are grouped in threes, there are three windows in the background and the form of Jesus resembles the three points of a triangle.
Countless copies have been made of this famous art work along with contemporary reinterpretations by Salvador Dalí and Andy Warhol.