According to the Wikipedia entry on the Radcliffe Camera, J. R. R. Tolkien “remarked that the building resembled Sauron's temple to Morgoth on Númenor.” That is not mentioned in the “The Readers Guide to the Bodleian Library.” At any rate, here is what the temple—or library, if you prefer—looks like from inside:
For a picture of the outside, see the third image on this post.