Take a look at amazing pictures of extraordinary libraries from around the world on the Curious Expeditions website. There are almost 100 libraries pictured, and each one is unique and beautiful.
My favorite picture is shown above. Even though it's pretty impossible to choose just one... I fell in love with the library of the Admont Abbey in Austria.
Thanks to Another Kick Butt Librarian for the link.
And for me, any library that lets me check out books is beautiful.