Smithsonian National Museum of Natural HistoryStop on Washington DC National Mall Walking Tour, a free self-guided tour.The green-domed building across the Mall is the National Museum of Natural History, open since 1910 and home to more than 145 million specimens and artifacts, most of them in research collections behind the scenes.Start in the rotunda, where an African bush elephant has greeted visitors since 1959. The museum's best-known object is the Hope Diamond, a 45.52-carat blue diamond on the second floor. Jeweler Harry Winston donated it in 1958 and sent it to the Smithsonian by registered mail in a plain package. Its reputation for bringing bad luck to its owners is a legend, much of it encouraged by people who wanted to sell it.The dinosaur hall reopened in 2019 as the Hall of Fossils - Deep Time, built around a Tyrannosaurus rex mounted in the act of attacking a Triceratops. The Sant Ocean Hall has a life-size model of a North Atlantic right whale, and in the Insect Zoo you can watch live tarantulas being fed.Admission is free. Plan at least two hours, more with children.Stops on this tourWashington MonumentNational Museum of African American History and CuNational Museum of American HistorySmithsonian National Museum of Natural HistoryNational Gallery of ArtUnited States CapitolUnited States Botanic GardenNational Museum of the American IndianNational Air and Space MuseumHirshhorn Museum and Sculpture GardenThe Smithsonian Institution Building - The CastleFreer Gallery of ArtJefferson MemorialWorld War II MemorialMartin Luther King Jr. MemorialKorean War MemorialLincoln MemorialVietnam Veterans MemorialWhite House EllipseWhite HouseLafayette Square