25. The Book of Kells, by Bernard Meehan (2012)
This is quite possibly the most beautiful book I've ever read. It's certainly the only one I've read with a magnifying glass handy to make sure I didn't miss any of the details.
I have seen the Book of Kells personally, but nothing prepares you for the wealth of fascinating detail that Bernard Meehan reveals in his erudite discussion of the book. He goes into its history, structure, script, illustrations, symbolism, authorship, physical structure and a whole lot more. Meehan highlights fine aspects of the illustrations that the untrained eye would never see, they are so tiny. The artistry and calligraphy he describes are breath-taking and engender awe for what these scribes and artists were capable of more than 1200 years ago.