This sister museum of the Clark Art Institute graces the center of town and has an incredible (free!) collection of its own. Around half of its 13,000 pieces comprise the American Collection, with substantial works by notables such as Edward Hopper (Morning in a City), Winslow Homer and Grant Wood, to name only a few. The photography collection is also noteworthy, with representation by Man Ray and Alfred Stieglitz. Did we mention it's free?
To find the museum, look for the huge bronze eyes embedded in the front lawn on Main St.