The Walters Art Museum in Baltimore–one of our Department’s CTPhD Program partners–was among the first museums to make images of many of the artworks in its collection freely available to the public way back in 2012. Ever since that time, you have been able to download high-resolution images of its works either on the museum’s own website or in Wikimedia Commons under a Creative Commons (CC BY-SA) license.
Now, the Walters has taken the unprecedented step of waiving copyright altogether and dedicating these images to the public domain (CC0). There are no longer any restrictions whatsoever on your use of these images. You don’t even have to say that they came from the Walters (although in general, crediting the source of an image is still considered a best practice whenever possible).
Note that this new policy does not apply to images of every artwork in the Walters’s collection. All of the images released into the public domain are of artworks that are themselves also in the public domain. If an artwork is copyrighted, the Walters does not have the authority to place images of it in the public domain. This means that most art made since about 1900 is still under copyright, so those images are not made available here. However, since the Walters focuses mainly on earlier periods, this restriction excludes a relatively small number of the works in its collection.