Article continues below advertisementWhen you think of a national museum, you probably picture marble halls and a hushed reverence for history. The U.S. Marshals Museum in Fort Smith, Arkansas, rips up that script. It's an architectural star on the Arkansas River-literally, the 53,000-square-foot structure is shaped like a Marshal's badge-and it delivers a shot of pure, unvarnished American grit. The museum is a premiere destination that has attracted over 150,000 visitors since its opening. It earns its spot among the country's best, and here are four reasons why.