"Birds of America" -- the $10 million book

' Naturalist John James Audubon's "Birds of America" sold at auction in London on Tuesday for $10 million, making it the world's most expensive book.

The book, which was sold by the auction house Sotheby's, was purchased by an anonymous telephone bidder.

"Birds of America" is oversize — more than 3 feet tall and 2 feet wide — with 435 illustrations. When first published in 1827, the images were printed in black and white and then hand-colored by specialists. The combination of accuracy and artistry make Audubon's work unique.

A much smaller, low-resolution — but entirely free — version of "Birds of America" is on view on the Audubon website, at http://web4.audubon.org/bird/BoA/BOA_index.html.

—Carolyn Kellogg