During World War II, the name “Los Alamos” was classified information. People referred to Los Alamos Laboratory as Project Y, Site Y, or the Zia Project, though locals called it “the hill”—a name that you’ll l hear residents use today. The canyons, mesas, and mountains surrounding Los Alamos were an ideal place for workers to escape the pressure of their jobs and relax. Civilian workers and scientists brought their families to “the hill,” and created a sense of community on the isolated mesa-top, even during this immense undertaking. In January of 1943, this secret city had just 1,500 residents. By the time the war ended in 1945, the population of Los Alamos had boomed to an estimated 8,200.

Tour the town today and walk in the footsteps of J. Robert Oppenheimer, the Laboratory's first Director, and Nobel Prize winners like Enrico Fermi, Emilo Segrè, and Richard Feyman. Discover where Manhattan Project staff lived and worked and learn the story of Los Alamos, the "secret city on the hill.”

In downtown Los Alamos, the Manhattan Project National Historical Park experience is a partnership between the Department of Energy, the National Park Service, Los Alamos County, the Los Alamos Historical Society, and private landowners.