The Last Supper is one of the western world's most famous paintings. It gained a great deal of attention recently due to Dan Brown's best-selling novel The Da Vinci Code.

Leonardo da Vinci painted The Last Supper on the wall of the dining hall at the Dominican convent of Santa Maria delle Grazie in Milan.

Jesus' last meal was a subject that almost every Renaissance (around 1400-1600) painter in Italy depicted at some point in their life.

Da Vinci chose a good spot for his painting - traditionally, Christian monks and nuns were expected to speak as little as possible at meal time, so it was common for church dining halls to display religious works of art for them to ponder while eating.

And what could be more relevant than the most famous meal in the Bible. Da Vinci has portrayed his interpretation of the scene described in the Bible when Jesus tells his followers that one of them will betray him.

Da Vinci painted the scene at the back of the dining room so that it would look like Jesus and his disciples are sitting at a table in the hall with the viewer.

Da Vinci's version of this biblical supper took him four years to complete. It took so long because the painting is large and detailed, but also because da Vinci was experimenting with a new technique.

This involved painting with tempera (egg yolk and vinegar), along with oil paints, on dry plaster.

Many people, including Brown, refer to the masterpiece as a fresco, which involves painting onto wet plaster so that the paint dries into the wall and becomes permanent.

There are several drawbacks to this technique. The colours are limited and an artist has to work fast before the plaster dries. And once it is dry, they cannot make any changes.

Da Vinci's dry-plaster technique meant he could work slowly and carefully and re-do parts if necessary.

And he did work slowly - his patrons were angry at the delay but he refused to go any faster.

Unfortunately, da Vinci's experiment was a disaster as humidity caused flakes of paint to fall off the wall almost immediately.

Over the years, vandalism and decay left the painting in a desperate state. The repairs, which took 20 years and meant the painting was closed to the public throughout the process, are now complete.

But it is still not easy to see the painting - only 20 people can visit the work at a time, and only for 15 minutes. Viewing is by prior arrangement only, and tickets sell out months in advance.

But if you are planning to visit Italy, seeing the painting in the flesh is worth the effort. Not many of your friends can surely boast having seen one of the world's most prized works of art.