These eye-bending visual puzzles will challenge your wits and reward your love of art. Great paintings, with their beautiful and sometimes hidden details, deserve a closer look. So open your eyes and see if you can spot the differences in each of these 40 ingenious fine-art puzzles. Every spread features two versions of a famous masterpiece—the original on the left and one with 20 subtle changes on the right. That comes to 800 changes altogether! So lose yourself in the iconography of Renaissance Florence, the still lifes of the Dutch masters, the Paris of the Impressionists, and more.