https://www.vice.com/en_us/article/qjdwaw/smithsonian-releases-28-million-incredible-images-into-public-domain

America’s Smithsonian Institution is the world’s largest museum system. The Smithsonian oversees 19 museums, nine research centers, various libraries and archives, the National Zoo, and 155 million separate artifacts. Now, for the first time, the Smithsonian has uploaded more than 2.8 million images from its collection online.

Even better, it’s put those images in the public domain under a Creative Commons Zero license. No rights are reserved and the public can do with the images of the Smithsonian’s treasures what it wishes.