Secret Cities

The Architecture and Planning of the Manhattan Project

may 3, 2018 – july 28, 2019

The Beginning

In the fall of 1942, less than a year after the United States was drawn into World War II by the Japanese attack on Pearl Harbor, the U.S. Army Corps of Engineers quietly began acquiring vast tracts of land in remote areas of three states. The few residents of these areas were summarily evicted and their houses demolished. Soon, thousands of young workers arrived from far and wide, initially occupying tents and other makeshift shelters within the newly designated military reservations.

secret cities
Aerial view of “Queen Mary” chemical separation plants at Hanford, Washington.
U.S. Department of Energy.

Shielded from public view by natural barriers and security fences, the workers quickly erected hundreds of buildings, ranging from prefabricated houses to industrial structures of unprecedented scale.

As they did so, thousands more residents arrived in a near-continuous stream. By the end of the war, a total of more than 125,000 people lived in the three cities that had been built from scratch on these sites. Yet these cities appeared on no maps, and the federal government did not acknowledge their existence. Unfathomable quantities of supplies were delivered, but very little seemed to come out, adding to the air of mystery surrounding these “Secret Cities.”

Manhattan Project Sites

That mystery unraveled on August 6, 1945, when the U.S. dropped an atomic bomb on Hiroshima, Japan, and President Harry S. Truman publicly revealed the purpose of the sites now known as Oak Ridge, Tennessee; Los Alamos, New Mexico; and Hanford/Richland, Washington. In roughly two and a half years, the Manhattan Project—so named because it was managed by the Army Corps’s Manhattan Engineer District in New York—had produced a weapon of previously inconceivable destructive force. While the ethics and strategic necessity of the decision to use such a weapon in combat are still fiercely debated, there is no question that this initiative was one of the most significant milestones in the history of scientific research and development.

The Manhattan Project would not have been possible without the extraordinary achievements in architecture, engineering, and planning that yielded three entirely new cities in a remarkably short time. Built in the early years of the modern movement, these cities reflected cutting-edge ideas about town planning, mass housing, civil and mechanical engineering, and modular construction. They became important proving grounds for the large-scale suburban development that would dramatically alter the physical and cultural landscape of the nation in the post-war era.


This exhibition is supported in part by an award from the National Endowment for the Arts. We also gratefully acknowledge Nancy Voorhees; Turner Construction CompanySkidmore, Owings, & Merrill and the Skidmore, Owings, & Merrill FoundationSTUDIOS ArchitectureBechtelthe Graham Foundation for Advanced Studies in the Fine ArtsHDR, Inc.; and ORAU for their generous contributions.