Gone with the Wind (1939)

The template for the whole genre: a romance stretched across the Civil War and Reconstruction, where Scarlett O'Hara and Rhett Butler spend years circling, marrying the wrong people and finally colliding at the worst possible moment. Vivien Leigh plays Scarlett as a survivor first and a lover second, which is exactly why the relationship stays tense rather than sweet. Go in knowing what it is: a Hollywood production that romanticizes the plantation South, and that framing has aged badly. Go in knowing the length too, close to four hours with an intermission. What still holds is the scale of the craft, and Clark Gable's Rhett, whose patience running out is the real climax.