From a gallery of beautiful libraries, the Biblioteca do Palacio Nacional da Ajuda Lisboa III, in Lisbon, Portugal:
[click on any picture for full-size; they're all well worth it.]
Not by any means the most gorgeous, just the one that for me strikes closest to the right balance between books, architecture, and art.
Then there’s the Vatican’s library, in which the books are completely overwhelmed:
How could you possibly read there? It’s hard to resist making parallels between this Library’s presentation of its books, and the Church’s presentation of its theology.
The legend on this photo says the books used to be chained to prevent theft:
However, fans of Terry Pratchett’s Librarian at the Unseen University’s Magical Library know better: the chains keep the books from escaping, or even attacking other books or unwary readers. (The Librarian himself is a victim of such an attack, and now presents as an orangutan. He’s resisted all efforts to change him back.)
Check out the entire gallery; there are some beautiful, beautiful pictures.