During a 2021 research trip, Nolan discovered that Los Alamos had drastically changed from its 1940s appearance and could not be used for exterior shots of the town; for example, the town's equivalent of a Main Street has a Starbucks. Instead, the production team constructed a version of 1940s-era Los Alamos on top of a similar plateau at Ghost Ranch. It took three months to build the set, which was used for only six shooting days. The general plan was to shoot only exterior shots on the set at Ghost Ranch, then shoot interior shots on location inside various historic buildings in the real town of Los Alamos. Interior shooting in Los Alamos began on March 8, 2022. Many scenes in the film take place in academic lecture halls; to save time and money, the production team decided against attempting to reconstruct those halls as sets at Ghost Ranch, and shot them inside a historic Women's Army Corps dormitory in Los Alamos. Scenes were also filmed in Oppenheimer's original cabin in Los Alamos, which had been restored. Kai Bird visited the set and was impressed by Murphy's performance. The New York hotel scenes were shot in Albuquerque's Old Post Office building, while the Washington, D.C. scenes were shot in state government buildings in the state capital of Santa Fe.