Astronomical pictures of Messier deep space objects (nebulae, clusters, galaxies, etc.) which are mostly public domain for private use. Some of the pictures, however, are under copyright, as indicated by a tag on the picture. Each picture has textual information to accompany it.
Collections of public domain posters. The categories include World War, WPA, Graphic Arts, and Performing Arts. You may search by keyword, but the site uses a custom Google search. Thus, browsing by category may be more efficient.
Around 5,000 images pertaining to the Civil War era (up to the middle of 1862). It is easiest to search images on this site by narrowing down the category. Categories pertain to many topics beyond the actual Civil War, such as transportation during that period, frontier life, and Native American culture.
Unusual and interesting images from out-of-copyright sources (magazines, illuminated manuscripts, books, etc.). The content is varied and ranges from Bestiaries to anatomy to futuristic drawings. You may search by category or time period.
*Note: While the images are public domain, the the essays written for The Public Domain Review are under a Creative Commons license. Read the usage policy for more information.
Public Domain Images
Public domain images: remix, redistribute, and use without restriction or permission!
Free photos for commercial and private use - no attribution necessary. Some photos may come from other websites, such as Shutterstock, which may not fall under public domain - check each photo to ensure that it is public domain.
The Picdrome gallery is divided by categories (e.g. Abstract, Food & Drink, Nature, Technology, etc.). You may also search for specific images, but the search will take you to a custom Google search of Picdrome, which makes viewing the photos a bit more difficult.
"All photos published on Unsplash are licensed under Creative Commons Zero which means you can copy, modify, distribute and use the photos for free, including commercial purposes, without asking permission from or providing attribution to the photographer or Unsplash."
Clip art of historical matters from prehistoric to present day. It may be easier to search by the time period and narrow down the categories rather than search by a specific keyword (more general searches, such as "egypt" or "abraham lincoln" do work well). Site discontinued.
This site allows you to search clip art images and collections, which are uploaded by various artists. These images may be downloaded and edited. If you choose to edit the image, you can do so on the site - add text, change colors, add shapes and stickers, re-size, enhance, etc. The altered image can then be downloaded onto your computer.