Leonardo da Vinci painted the most famous dinner in history on a wall the monks used as a dining room, so it was only a matter of time before they changed it. In 1652 the friars of Santa Maria delle Grazie in Milan cut a doorway through the bottom of the wall. The door took out the lower center of the painting, including Christ's feet, and you can still see the arch in the middle of the table today.
That is not the only thing that has gone wrong with it. Leonardo hated the speed of true fresco, where you paint on wet plaster and cannot go back. He wanted time to revise, so he painted in tempera on dry plaster, an experiment that began failing within his own lifetime. Paint flaked and faded for centuries, and restorers have been at work on it for most of the time since. The most recent restoration took from 1978 to 1999.
The composition is a masterclass in planning. Leonardo placed a nail in the wall at the vanishing point, near Christ's right temple, and stretched strings from it to mark the perspective lines of the ceiling and walls. The nail hole is still there. Around the table, the apostles break into four groups of three, each reacting to Christ's words, one of you will betray me. Judas leans back from the group, clutching a small bag and tipping over the salt.
A story told by the writer Matteo Bandello says Leonardo worked on it for hours at a time, and then did nothing for days. When the prior of the convent complained to the duke, Leonardo reportedly said he would use the prior's face for Judas.
In August 1943 Allied bombs destroyed much of the convent. The refectory wall survived because it had been protected with sandbags.
Leonardo's The Last Supper appears on our: