The "Vertigo shot" and
the oneiric narrative

The "Vertigo shot" or dolly zoom was created by simultaneously zooming in and tracking backward; the result is that the foreground remains stable while the background expands backwards. The shot was done using a model of the tower stairs laid horizontally on its side. The Vertigo shot has been widely imitated.

An explanation of the shot, from YouTube
Examples of the Vertigo shot from Vertigo, Jaws, Poltergeist, Goodfellas, and Lord of the Rings I
Another example, from
La Haine.
The effect in a video game.
A list of movies, TV, and videos where the effect is used.(Not all these listings are accurate; the author confuses extreme telephoto lens effects with the Vertigo shot.)

The oneiric narrative: is it all a dream?
How does Scottie get down from his dangling position at the start of the story? One critical theory is that he doesn't, that the entire movie is a hallucination, an oneiric narrative. Vertigo ends as it begins, with Scottie staring down helplessly from a great height--though with his vertigo cured.

Hitchcock shot an additional scene for Vertigo, never used, which would change the frame. See discussion of this and other possible changes to the movie.