Here is a great restoration story from the History Blog.
The Dulwich Picture Gallery in London unveiled the results of a two-year restoration of Saint Cecilia, a Baroque masterpiece currently attributed to the school of Annibale Caracci. The 17th century painting was in such awful condition that it had been off public display and in storage since the late 19th century. In 2009, sufficient funds were raised to begin a full restoration and it’s taken this long to painstakingly repair tears, reframe and clean the work.
Read the rest there and check out the hi-res “before and after” image of the painting.