I’ve only just encountered Fathom: The Source for Online Learning: provided by Columbia University, it “offers access to the complete range of free content developed for Fathom by its member institutions”, which include the British Library, V & A, University of Chicago and American Film Institute. Not just historical either - it covers a wide range of fields.
I stumbled on it when looking at this seminar on visual images of Women Who Ruled in early modern Europe, from the University of Michigan. Pretty fab stuff. (And I’ve just added several new resources from the site to EMR. This is really impressive, and I can’t believe I missed it before…)