While Googling pictures of books and libraries for a little project of mine, I came across the world's greatest library, in my humble opinion of course.
This is The Duke Humphrey Reading Room. Although, it was better known to me as the Hogwarts Library from the Harry Potter movies! I gasped upon seeing this image pop up in my search results because I recognized it instantly. It's best known from the first of the five currently released films. Harry, Ron, and Hermione are pouring over the ancient books in search of information about Nicholas Flamel, the only known owner of the sorcerer's (or philosopher's) stone.
Hmm... I wonder if their restricted section screams as loud as it did in the movie... (clearly kidding!)