The Manhattan Project, the secret US government program that produced the world’s first atomic weapons during World War II, left a complicated legacy in its wake. It brought the second world war to a close, but laid the groundwork for the Cold War. It was responsible for the deaths of over 125,000 Japanese citizens, the majority of whom were civilians. It ushered in the atomic age as scientists and businesses sought ways to use “atoms for peace,” leading to advances in medical imaging, the rise of nuclear energy, and even “atomic gardening.”

It also gave us the cities of Oak Ridge, Tennessee; Richland and Hanford, Washington; and Los Alamos, New Mexico, cities that were created as part of the Manhattan Project and whose existence remained a closely-held secret during the war. These cities are the subject of Secret Cities: The Architecture and Planning of the Manhattan Project, an exhibition currently on display at The National Building Museum in Washington, D.C.

At a recent lecture, senior curator Martin Moeller delved into the planning, architecture, and cultural legacy of these cities — their lasting impact on the industries of the built environment. He began by pointing out that, in terms of design, there was little revolutionary about these towns. Precedents for planned communities existed in developments such as Olmsted and Vaux’s Riverside, Illinois; the Garden City Movement; and the work of Scottish biologist and city planner Sir Patrick Geddes.

What makes the cities of the Manhattan Project significant, however, was the scale of their design and speed of their construction. Moeller pointed out that, unlike earlier examples of community planning, these cities had to be entirely self-contained due to the nature of the work being carried out there.

In the case of Oak Ridge, architecture firm Skidmore, Owings & Merrill (SOM) was responsible for the design of an entire city that would be home to 75,000 residents by the end of the war.

Moeller explained that SOM went from “being architects to being planners and civil engineers, and soon they were going to becoming construction engineers, interior designers, and even designers of the school curricula in the schools within Oak Ridge.”

In addition to being planned in utmost secrecy, Oak Ridge and other Manhattan Project cities had to be constructed at a breakneck pace. “During the height of the war, the contractors building these houses were turning over the keys to the government to one house every thirty minutes,” said Moeller.

The speed of construction was possible thanks to advances in prefabrication technology. Houses at Oak Ridge were constructed using Cemesto boards, a prefabricated product made of compressed cement and asbestos fibers, and were built in an assembly line fashion, a technique that developer William Levitt would later use in the construction of his Levittown developments.

Given the speed at which these cities were constructed, one of the more remarkable aspects of their design is the inclusion of green, walkable community space. “This is extraordinary,” argues Moeller. “This is an emergency situation, where people are thinking that we are in a race against time, and we’re being careful to preserve large trees and create greenbelt spaces between houses.”

This also raises provocative questions about modern day development practices. If the planners of these communities were able to take the time to preserve existing natural features and integrate green space under extraordinary circumstances, why do we find it so difficult to do the same thing today?

There were darker aspects to these cities as well. Land for the developments was seized from existing residents via eminent domain; property owners were told that the land was needed for a “demolition range.” In Oak Ridge, this primarily impacted poor subsistence farmers. In Washington, the government seized land from the Wanapum people, a Native American group that traces its identity to the region and the Columbia River that runs through it.

Race also played a part in the story of these cities. For example, segregation was designed into the plan for Oak Ridge. African American residents were forced to live in “hutments,” small, single-room structures with minimal protection from the elements. The hutments were separated from the city and further segregated by sex, dividing up families and adding further insult to the indignity of being forced to live in substandard housing.

Despite a complicated social and political legacy, for Moeller, the urban design legacy of the Manhattan Project is clear. “The real thing to come out of this, in terms of architectural and planning history, is the emergence of the modern architecture-engineering-construction firm.”

By the end of WWII, SOM had grown to 650 employees, and would eventually become “arguably the single most influential corporate architectural firm in the post war era.”

In their work on Oak Ridge, SOM took on an expanded role as “architect, engineer, planner — all these things really beyond the scope of what architects had ever done.” Because of this experience, “they were uniquely prepared coming out of WWII to design for the new world, creating corporate campuses and communities on a scale that we wouldn’t have even been conceived of before.” They paved the way for the business model that would come to define the planning and design industries in the second half of the 20th century.

Secret Cities: The Architecture and Planning of The Manhattan Project is on display at the National Building Museum in Washington, D.C. through March 3, 2019.