How big is the world's biggest book? The Guinness World Record goes to "This the Prophet Muhammed," a 16-foot tall, 13-foot wide giant with 429 pages. Also, the book that explains Brazil's rules for paying taxes is ridiculous: it's 6 feet 10 inches tall, and has more than 41,000 pages. But the heavyweight winner might be "The Pali Canon" (Buddhist scripture), whose 1,460 pages are actually 5-foot stone tablets. Tough to carry in your backpack!