Happy birthday to the Flickr Foundation - the biggest, best archive of no-restriction, public domain photos on the web, with over 100 participating institutions, including the Library of Congress!
They are taking the “access” part seriously - making sure that the competing priorities of “getting and storing everything” and “letting everyone use everything” don’t come down on the side of a vast, musty archive that no one sees - and no one defends when it’s on the chopping block.
You can already search Flickr for millions of CC images, but these come with strings attached, requirements for attribution and follow-on licensing. The Commons, on the other hand, is entirely free to use. Search for yourself!