When writing about art, it is usually a good idea to include the piece of art you are writing about! You will want to find an image that you can easily locate and access and download. The sites listed below are open to the public and contain images that are in the public domain (meaning that they are no longer under copyright). Some images may still be in copyright, but as long as you are using it for academic purposes and cite the image, you should be okay.
Want to know more about fair use? Check out the "Copyright and Fair Use" tab.