Adams uses the 1953 film, Roman Holiday, starring Audrey Hepburn and Gregory Peck, as a structural framework for her narrative as well as a motif that symbolizes the novel’s thematic engagement with Loving Things for Sentimental Reasons. Amelia loves Audrey Hepburn movies because they remind her of her early relationship with her mother, and Roman Holiday signals Amelia’s attempts to reconnect with her truest self throughout the novel. In the movie, Hepburn’s character is a princess who has grown tired of her exhausting tour of European capitals. When she meets Peck’s character in Rome, the princess pretends to be a regular person and enjoys herself in the Italian capital. In the film, the princess knows her duty is to her country and her family, and she returns to her real life, leaving Peck’s character behind. As Amelia’s favorite film, Roman Holiday inspires her decision to road trip to Rome, Kentucky, the novel’s inciting incident.

Throughout When in Rome, Adams parallels Amelia’s arc with the arc of the princess in the film. Such a structural parallel raises the stakes of Amelia’s final choice between returning to the restrictions and responsibilities of her previous life as the princess did, or breaking from the film’s structure and writing herself a different ending.