Run by the U.S. Forest Service on the bluffs above the Missouri, this is the best Lewis and Clark museum on the entire trail. The building itself is shaped to evoke the great cottonwoods the expedition camped under. Exhibits cover the full 8,000-mile journey but with proper emphasis on the punishing month-long portage around the five falls of the Missouri — what Meriwether Lewis called "the grandest sight I ever beheld" and also the hardest stretch they faced.
Two films, a research library, and a long ramp of life-size dioramas walk you through the expedition chronologically. The site also serves as the headquarters for the Lewis and Clark National Historic Trail. Allow two hours; the view of the river from the back deck alone is worth the stop.