Manhattan Project National Historical Park


The Manhattan Project is one of the most transformative events of the 20th century. It ushered in the nuclear age with the development of the world’s first atomic bombs. The building of atomic weapons began in 1942 in three secret communities across the nation. As World War II waned in 1945, the United States dropped the atomic bombs on Hiroshima and Nagasaki, Japan—forever changing the world.

Manhattan Project National Historical Park is located in three states: New Mexico, Tennessee, and Washington. For more information on accessing each of these three units, visit our Directions & Transportation page.

  • Guided Tours
  • Junior Ranger Program
  • Museum Exhibits

  • Science, Technology and Innovation
  • Wars and Conflicts
  • World War II

Top Secret!

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The Manhattan Project was a top-secret project focused on building the world's first atomic weapons.

B Reactor Under Construction

Black and white photograph of a construction site with scaffolding and workers visible.

Constructing the B Reactor, the world's first full scale nuclear reactor, took hard work and ingenuity.

Ashley Pond

a landscaped pond with fountain in front of snowy mountains and a blue sky with clouds

Ashley Pond has been a central part of the Los Alamos community since the days before the Manhattan Project.

Bruggemann Ranch

Color photograph of a large field of wild grass with a stone building in the background.

The Bruggemann Ranch was a major farm that was forcibly evacuated to create the Hanford Site.

Oppenheimer and Groves at Trinity Test Site

Two men stand next to a mangled piece of metal equipment in the desert.

J. Robert Oppenheimer and Gen. Leslie Groves at the Trinity Test Site.

The Gadget

A man stands next to a complicated, spherical device covered in wires

Norris Bradbury stands next to the Gadget, the device used in the Trinity Test.

Calutron Girls

black and white photo of group of women sitting at their individual stations in the Y-12 plant

The Calutron Girls operated the arrays, or “racetracks”, at Oak Ridge’s Y-12 Electromagnetic Isotope Separation Plant during the Manhattan Project.

International Friendship Bell

Ranger facing a large bronze cast bell hanging from an abstract pavilion surrounded by green space

The International Friendship Bell in Oak Ridge, Tennessee symbolizes peace and reconciliation between the United States and Japan.