This treasure trove of Yellowstone history houses 720,000 cultural and historic items, an archaeology lab, herbarium, research library, and the park’s archives. You can drop in to see the historic exhibits anytime, but I highly recommend reserving a spot on the free, twice-weekly behind-the-scenes tour (late May to early Sept Tues and Thurs at 8:30am) for an up-close look at wildlife specimens, rare native plants, historic photos, original Thomas Moran sketches, and more.