A multi-site, multi-state endeavor

Manhattan Project National Historical Park (MAPR) is a park in three distinct parts, each of which helps tell the story of the people, the events, and the science and engineering that helped end World War II.

Featuring landscapes and structures from the early 1940s (and beyond), MAPR allows visitors to explore how atomic weapons changed the world. MAPR strives to address both the controversy of the Manhattan Project and its contribution to history and our modern world.

Los Alamos, New Mexico, is one of the three MAPR sites. It features landmarks in downtown Los Alamos that are available to visit year-round, as well as landmarks “behind the fence” at Los Alamos National Laboratory. Some of these landmarks are accessible to the public a few times per year; see upcoming tours. The Department of Energy is developing phased access to its other properties in alignment with its national security mission.

The preservation and interpretation of all MAPR sites will show visitors the scientific, social, political, and cultural stories of the people who ushered in the atomic age.

LANL sites

Battleship Bunker, 1944 image

Battleship Bunker, 1944

TA-18-2 was constructed to support implosion diagnostic tests related to Fat Man design development. Experiments using the magnetic method, carried out at Pajarito Site, detected changes in a magnetic field during a high-explosives shot. TA-18-2 is a robust, cast-in-place concrete bunker. It is known as a battleship building because the west end of the building is bow shaped and shielded with steel plate.

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Concrete Bowl, 1943 image

Concrete Bowl, 1943

Two Mile Mesa Site, also known as TA-6, was used as an outdoor research area to develop plutonium recovery methods in the event that the Trinity test failed. One of the most visible legacies of this research is a large, 200-ft-diameter concrete bowl. The bowl was used for the water recovery method, which involved detonating high explosives experiments using natural uranium as a stand- in for plutonium.

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Gun Site, 1943 image

Gun Site, 1943

During Project Y, Los Alamos researchers also developed the Gun Site, known in 1943 as Anchor Ranch Proving Ground, to design and test nuclear weapon prototypes. At this site, scientists, engineers, and ordinance experts conducted experiments on the inner workings of a “gun-type” atomic bomb design, hence the site’s name.

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K-Site, 1944 image

K-Site, 1944

More than 12 testing areas were developed at Los Alamos to support the design of a new plutonium weapon. This research included the use of varied diagnostic methods to understand the inner workings of implosion, an inward explosive force that was key to the Fat Man weapon design.

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L-Site, 1944 image

L-Site, 1944

TA-12-4 is a firing pit constructed of heavy timber for use in high-explosives experiments that supported implosion research. The Los Alamos Terminal Observation Group used TA-12 as its firing site. Physical remains of explosives firing tests were examined after each shot, hence the term “terminal observation.” World War II facilities included the firing pit, a personnel shelter, and several storage buildings and magazines. The pit is 12 feet deep and lined with steel to protect the structure from explosive blasts.

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Pond Cabin, 1914 image

Pond Cabin, 1914

Originally built by Ashley Pond as an office for a private Sportman’s Club, the cabin was used by physicist Emilio Segrè’s group during the Manhattan Project to support plutonium chemistry research.

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Q-Site, 1944 image

Q-Site, 1944

TA-14-6 is a small, wood-frame building used as a darkroom and shop to support small scale implosion tests. At Q-Site, users conducted terminal observation experiments and studied cylinder implosions using the flash photography method. This implosion diagnostic tool relied on high-speed photographic equipment, including the rotating prism camera. Wartime facilities included a control building, high-explosives magazines, firing chambers, and the TA-14-6 shop and darkroom building.

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Quonset Hut, 1945 image

Quonset Hut, 1945

Building TA-22-1, a Quonset™ hut, is one of the most historically significant properties at the Laboratory. Manhattan Project scientists and engineers worked on the final design of the Fat Man weapon in this facility, perfecting the “trap door” design shortly before the end of the war. Fat Man’s high-explosives sphere and associated components were assembled in this building and then transported to Tinian Island. After the war, the building was used as a detonator research facility for almost 40 years.

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S-Site, 1944 image

S-Site, 1944

TA-16-58 is a one-story, single-room, high-explosives storage magazine. This small building was constructed with a reinforced-concrete floor and walls. The magazine is encircled by a protective earthen berm, and its roof is built of wood to serve as an upwards path for the force of an accidental explosion. This building is the last remaining high-explosives facility built specifically to support S-Site operations during the Manhattan Project.

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Slotin Building, 1946 image

Slotin Building, 1946

The high-bay addition at TA-18-1 was constructed in1946, at the end of the Manhattan Project era, and supported criticality research at the wartime Laboratory’s Pajarito Site. This building addition was the location of the May 21, 1946, criticality accident, which occurred during an experiment known as “dragon-type experiment” and led to the death of scientist Louis Slotin.

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V-Site, 1944 image

V-Site, 1944

V-Site was constructed to support the assembly of the Fat Man implosion weapon. It was also used to assemble the high-explosives sphere for the Trinity device or Gadget. The site originally consisted of six buildings, but four were destroyed during the May 2000 Cerro Grande Fire. The first building at V-Site was built in early 1944. TA-16-517, as it is known today, is a small triangular-shaped building surrounded by an earthen berm.

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Virtual tour of the historical sites

Discover the stories, people, and locations behind the Manhattan Project with our interactive virtual tour.

Downtown Sites

Ashley Pond image

Ashley Pond

Ashley Pond is named after the founder of the Los Alamos Ranch School. Today it is a public park and center for community events.

Bathtub Row image

Bathtub Row

The homes on this street were built for the Los Alamos Ranch School and were adapted during the Manhattan Project for use by scientists. The street got its name because they were only homes in town with bathtubs during WWII.

Bradbury Science Museum image

Bradbury Science Museum

Over 60 interactive exhibits trace the history of the Manhattan Project, and describe Los Alamos National Laboratory's defense and technology research projects.

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Fuller Lodge image

Fuller Lodge

Fuller Lodge was built in 1928 as the dining hall for the Los Alamos Ranch School. During Project Y, the Lodge hosted community activities for lab employees. On Wednesdays come explore this wonderful log building!

Hans Bethe House image

Hans Bethe House

Chemist Edwin McMillan and physicist Hans Bethe, both Nobel Prize winners, lived in this house. Inside, you will find the Harold Agnew Cold War galleries, part of the Los Alamos History Museum. Tickets are available at the History Museum.

Ice House Memorial image

Ice House Memorial

This memorial contains original stone from the Ranch School’s ice house, which was torn down in 1957. Project Y scientists used the ice house to assemble the nuclear components of the Trinity gadget, the first tested atomic device.

Los Alamos History Museum image

Los Alamos History Museum

Built as the infirmary for the Ranch School in 1918, it later served as a guest cottage for Ranch School visitors and was Gen. Leslie Groves’ favorite place to stay in Los Alamos. This museum features exhibits on the Manhattan Project, as well as the people of Los Alamos from ancient through contemporary times.

Oppenheimer & Groves Sculpture image

Oppenheimer & Groves Sculpture

You can see sculptures of Dr. J. Robert Oppenheimer, scientific head of the Manhattan Project, and Gen. Leslie Groves, military head of the Project.

Stone Power House image

Stone Power House

This structure was built in 1933 to house the Ranch School’s electrical generator. A er remodeling it in 1944–1945, explosives expert George Kistiakowsky lived here.

Manhattan Project Visitor Center image

Manhattan Project Visitor Center

Pick up your park guide, get one of the special three-part stamps in your passport, see a short film about the Project, and pick up your Junior Ranger booklet for the kids. Welcome to your tour of Project Y, the Manhattan Project’s Los Alamos Site!

WWII Cafeteria image

WWII Cafeteria

This building was the favorite mess hall for the military members of the Project. Now it is the Los Alamos Performing Arts Center.

Women's Army Corps Dormitory image

Women's Army Corps Dormitory

This dormitory housed some of the WAC staff stationed here. Now it is the privately-owned Christian Science Reading Room; no visitors, please.

Other sites

Manhattan Project Historical   Oak Ridge Site

The Manhattan Project at Oak Ridge, Tennessee

Several massive Manhattan Project facilities at Oak Ridge enriched uranium for use in Little Boy, the atomic bomb dropped on Hiroshima, Japan on August 6, 1945. Today the story of the Manhattan Project at Oak Ridge includes historic sites, community centers and museums, and highly-secured nuclear research facilities operated by the US Department of Energy.

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Manhattan Project Historical   Hanford Marquee

The Manhattan Project at Hanford, Washington

Nuclear reactors at Hanford (now the Hanford Site) produced plutonium for the Manhattan Project to fuel the first atomic test and the Fat Man atomic bomb dropped on Nagasaki, Japan on August 9, 1945. The story of the Manhattan Project at Hanford encompasses historic facilities and educational centers with the National Park Service, the US Department of Energy and the communities where Hanford workers and their families lived, which are all part of the Tri-Cities region today.

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