It's never good when a famous painting gets damaged! There are different types of damage that can affect paintings, some of them accidental, some intentional – such as the vandalism which affected The Rokeby Venus in 1914.
A lot of the work done here at National Gallery is actually repairing the damage to paintings. There is a painting that was very difficult for the gallery to fix!

Marina Ventura and The Micro-Gridders: The Super Squad
05:17

The Circular Trail: a free Time Hunters history walk around the City of London
46:10

Marina Ventura and The Micro-Gridders: The Power Stash
05:25