Imagine several photos that appear identical at first glance, but which contain subtle differences that only a discerning eye can spot. In Ultimate Picture Puzzles, readers will have to use all their powers of observation to spot the differences in photos showing groups of people, iconic landmarks, and multitudes of animals. With meters measuring the difficulty of each puzzle, boxes for readers to fill in their times and keep track of their progress, and—for those who just can't spot the difference—an answer key in the back of the book, Ultimate Picture Puzzles is filled with the best brain-teasers for anyone looking for a visual challenge.