Although the news coverage surrounding the film's release implied that most of the film was shot in New Mexico, the official making-of book Unleashing Oppenheimer revealed that many of the film's most important scenes were shot within the studio zone in Los Angeles County. Early on, three days were set aside for filming at UCLA 's Kerckhoff Hall, which was used for both the Cambridge and Göttingen scenes. The Millennium Biltmore Hotel in Downtown Los Angeles stood in for the Mark Hopkins Hotel for one of Oppenheimer's encounters with Tatlock, for the Plaza Hotel for Strauss's 1949 birthday celebration, and for an unnamed Washington, D.C. hotel for the scene where Szilard and Hill try to get Oppenheimer to sign a petition against dropping the bomb on Japan. Oppenheimer's security hearing was shot in Alhambra, California, in a "disused office building in the former manufacturing headquarters for the petrochemical company C.F. Braun & Co." The scene in which Oppenheimer's security clearance was revoked was shot on May 19, 2022, the production's last day in Alhambra.