Leonardo da Vinci's 'The Last Supper' is painted onto the wall of what type of building?

The Last Supper is a late 15th-century mural painting by Leonardo da Vinci in the refectory of the Convent of Santa Maria delle Grazie, Milan. It is one of the world's most famous paintings.

The work is presumed to have been commenced around 1495-1496 and was commissioned as part of a plan of renovations to the church and its convent buildings by Leonardo's patron Ludovico Sforza, Duke of Milan. The painting represents the scene of The Last Supper of Jesus with his disciples, as it is told in the Gospel of John, 13:21. Leonardo has depicted the consternation that occurred among the Twelve Disciples when Jesus announced that one of them would betray him.

Due to the methods used, and a variety of environmental factors, as well as intentional damage, very little of the original painting remains today, despite numerous restoration attempts, the last being completed in 1999.