New National Building Museum exhibit explores the architecture of the Manhattan Project

Secret Cities: The Architecture and Planning of the Manhattan Project is a new exhibition at the National Building Museum that explores the highly classified effort to produce the atomic bomb. The exhibit places an emphasis on showcasing the three new “secret cities” that were built to accommodate the tens of thousands of people who worked on the project.

Oak Ridge, Tenn., Hanford/Richland, Wash., and Los Alamos, N.M., will be explored through original documents, photos, artifacts, maps, and models. The three cities were built from scratch by the U.S. government to accommodate the vast number of people and large-scale, secure facilities necessary for the project.

The K-25 plant was built for the enrichment of uranium through gaseous diffusion, in which gaseous U-235 was separated from U-238 through an incredibly fine mesh. When completed, K-25 was the largest building in the world under one roof. National Archives and Records Administration.

The cities, which were built in about three years, were heavily reliant on prefabricated construction and helped test and develop emerging ideas about planning and design.

The exhibition also touches on the postwar development of the cities, which remain centers of scientific research today. For more information, click here.

During World War II, the U.S. military erected thousands of prefabricated or semi-prefabricated houses across the country. One of the most common houses in Oak Ridge was the B-1 model, commonly known as the Flat Top. Each of these houses was built in a factory and transported by truck in two or three pieces to the site, where it was assembled atop a foundation. The architectural firm of Skidmore, Owings & Merrill (SOM) oversaw the planning of the city and the design and construction of most buildings within it. National Archives and Records Administration.

The camp for construction workers at Hanford ultimately housed upwards of 50,000 people, making it the fourth largest “city” in the state of Washington. Item courtesy of the U.S. Department of Energy, Hanford Collection.

The B Reactor at Hanford was the world’s first large-scale nuclear reactor. It produced plutonium for the device tested at the Trinity site in New Mexico on July 16, 1945, and for the bomb that was dropped on Nagasaki, Japan, on August 9, 1945. The B Reactor was permanently shut down in 1968, and is now being converted into a museum. National Archives and Records Administration.

Retail establishments at Hanford during the war, including this branch of the famed Sears, Roebuck chain, typically occupied very modest buildings. Item courtesy of the US Department of Energy, Hanford Collection.

Sophisticated equipment was used to monitor and control the potentially hazardous industrial processes at the K-25 plant and other Manhattan Project facilities. National Archives and Records Administration.