Not sure how long this project of Google has been going but it has fantastic photos of some of the very best art and the quality of the photos are amazing.
Below I've copied in a little of the FAQ about the Art Project and also the link
The Art Project is a collaboration between Google and 151 acclaimed art partners from across 40 countries. Using a combination of various Google technologies and expert information provided by our museum partners, we have created a unique online art experience. Users can explore a wide range of artworks at brushstroke level detail, take a virtual tour of a museum and even build their own collections to share. Few people will ever be lucky enough to be able to visit every museum or see every work of art they’re interested in but now many more can enjoy over 30 000 works of art from sculpture to architecture and drawings and explore over 150 collections from 40 countries, all in one place