"Did you know that more than 180,000 of the items in our Digital Collections are in the public domain?
"That means everyone has the freedom to enjoy and reuse these materials in almost limitless ways. The Library now makes it possible to download such items in the highest resolution available directly from the Digital Collections website.
"No permission required. No restrictions on use."
This is an amazing, rich and valuable free resource. Be sure to check it out, here.