While filming took place in the main reading room of the New York Public Library (they could film only early and had to be out by 10:00 am), the basement library stacks were represented by the Los Angeles Central Library as Reitman said they were interchangeable. The stacks were destroyed in a 1986 fire. The Millennium Biltmore Hotel stood in for the scenes set at the fictional Sedgewick Hotel. Principal photography concluded at the end of January 1984, after between 55 and 62 days of filming.