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Gun Site

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Anchor West Site; Anchor Ranch Proving Ground; Technical Area 8
1943–1944, Leslie Groves, J. Robert Oppenheimer, U.S. Army Corps of Engineers, and Willard C. Kruger. Los Alamos National Laboratory.
  • (Courtesy of Los Alamos National Laboratory)
  • (Courtesy of Los Alamos National Laboratory)

Named after a former ranch, the Anchor West Site or Anchor Ranch Proving Ground in Technical Area 8 contains four structures known as the Gun Site. While the basic technology of military ordnance was well established, the cannon barrel of the gun-type atomic bomb required high-alloy tubes manufactured to precise specifications and consequently required testing. The site was in use by September 1943, though the first test guns did not arrive from the Naval Gun Factory until March 1944. The tests were documented with high-speed photography.

Three structures housed laboratories and shops. Constructed of board-formed, cast-in-place reinforced concrete, the buildings face north along one side of a ravine and back protectively against earth berms that also cover their roofs: this placed them safely below the level of the gun emplacements to the south. Except for lites in the entry doors, there are no exterior windows. A central laboratory and shop building (TA-8-1) abuts a second laboratory (TA-8-3) at an oblique angle to the east and stands across an access road to the west from a shop and storage building with a rounded or “boat-tail” corner (TA-8-2). TA-8-1 originally had a wooden observation tower, to the right of the concrete loading dock, from which the proving ground with its gun emplacements to the south could be monitored.

The fourth structure (TA-8-172) is a portable wooden guard shack of a type that was once common throughout Project Y. All four structures are included in the Manhattan National Historical Park.


Los Alamos National Laboratory. The History and Legacy of the Manhattan Project at Los Alamos National Laboratory. Los Alamos, NM: Los Alamos National Laboratory, 2015.

McGehee, Ellen, Sheila McCarthy, Ken Towery, John Ronquillo, Kari Garcia, and John Isaacson. Sentinels of the Atomic Dawn: A Multiple-Property Evaluation of the Remaining Manhattan Project Properties at Los Alamos (1942–1946). Historic Building Survey Report No. 215. Los Alamos: Los Alamos National Laboratory, 2003.

National Park Service. Manhattan Project Sites. Special Resource Study/Environmental Assessment. Washington, D.C.: Department of the Interior, 2010.

Writing Credits

Christopher C. Mead
Christopher C. Mead
Regina N. Emmer

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