East African Lion Exhibit, National Museum of Natural History, by Unknown, 1915, Smithsonian Archives - History Div, In April of 1913, East African lions, from the Smithsonian-Roosevelt African Expedition (1909-1910) and mounted by George B. Turner, are placed on display in Mammal Hall in the new United States National Museum, now the National Museum of Natural History. The building opened in 1910. Pictured are three full-grown East African lion with two cubs in a lifelike pose at an African water hole..