From the Wikimedia Blog Post:
The Walters Art Museum in Baltimore, Maryland, has donated more than 19,000 freely-licensed images of artworks to Wikimedia Commons. The Walters’ collection includes ancient art, medieval art and manuscripts, decorative objects, Asian art and Old Master and 19th-century paintings. The images and their associated information will join our collection of more than 12 million freely usable media files, which serves as the repository for the 285 language editions of Wikipedia.
The image donation is part of the Walters Museum’s larger initiative to provide free public access to its collection, both online and offline, beginning with the removal of admission fees in 2006. In 2011, the Walters launched a redesigned works of art website with 10,000 online artwork images freely licensed under a Creative Commons license.