Here's a wonderful post of beautiful libraries from Curious Expeditions. I've written about a few before, including the Boston Copley Square Library and Beinecke Library at Yale.
More ecclesiastical design from WebUrbanist - this time, it's 15 Amazing Monasteries, Sanctuaries and Abbies. I'd like to point out, though, that there are really only 14 on the list, as the Monastery at Petra is not actually a monastery.
What's behind the bookcase?
Find out at Apartment Therapy.
I also found online directions to build a bookshelf door for your very own secret room.