Project Gutenberg is a collection of public domain ebooks.
NGA Images includes public domain digital images from the National Gallery of Art’s collections.
Flickr Commons is a collection of images from a wide variety of museums, libraries, archives, and other cultural institutions.
The Prelinger Archives is a collection of public domain ephemeral films, including advertising educational, industrial, amateur, and so on.
NASA-GRIN is a collection of public domain NASA photos.
Chronicling America is a collection of American newspapers published before 1923 and therefore in the public domain.
O Say Can You See gathers together public domain legal and personal records, specifically in the following categories:
- All petitions for freedom cases originating in the D.C. Circuit Court sittings in Washington and Alexandria, 1800-1862
- Civil Cases involving African American families, 1800-1820
- Chancery Records involving African American families, 1800-1820
- Criminal Records involving African American families, 1800-1820
The project distributed under a Creative Commons license.
The Getty Museum’s Open Content Program contains images that are either in the public domain or whose rights are held by the Getty. They can be searched here.
HathiTrust is a collection of digitized books, government documents, and ephemera in the public domain, primarily held by university libraries.