Devils Tower is a dramatic geologic feature that juts out of the rolling prairie surrounding the Black Hills region in Wyoming, and it became the first national monument in the country in 1906. It might seem like a majestic mountain, but it’s actually made of molten rock that hardened into fascinating geometric columns. This site is sacred to multiple Native American tribes, and its mythical quality led to it being featured in the sci-fi movie “Close Encounters of the Third Kind.” It’s still the setting for Native American ceremonies as well as a popular destination for rock climbing and hiking.