Free Images, Free Photos, and Free Art, Many from Museums, such as the Museum of Natural History’s newly digitized archives. These include the Metropolitan, Getty, Cleveland, and many others.
http://m.washingtonpost.com/blogs/style-blog/wp/2014/05/01/19-legitimately-astounding-photos-from-the-museum-of-natural-historys-newly-digitized-archives/?tid=sm_fb
Getty Museum « Open Culture Open Culture
http://www.openculture.com/2014/01/download-over-250-free-art-books-from-the-getty-museum.html