Museum websites offer high quality images of items in their collections as well as interpretive text to jumpstart your exploration. Other sites to try include national libraries in Europe and those of major ecclesiastical buildings (e.g., Notre Dame de Paris).
Use the recommended resources on this page to find high-quality art images.
Ancient Castle, Georgette Agutte, 1903, Smithsonian American Art Museum
We recommend these image databases:
Google Images is an excellent starting point for exploratory research, but be sure to expand the search further!
Should I cite images?
How do I cite images?