The "Vertigo effect"

The "Vertigo effect" (also called dolly zoom or push-pull) was created by simultaneously zooming in and tracking backward; the result is that the foreground remains stable while the background expands backwards. The effect creates a visual equivalent of the disorientation Scottie experiences due to vertigo and acrophobia.

The shot was created using a model of the tower stairs laid horizontally on its side, with the camera on a track.

The Vertigo effect has been widely imitated.

A clip from Vertigo showing the effect.
An explanation of the effect, from YouTube
An explanation from YouTube featuring examples from Jaws, Poltergeist, Goodfellas, and Lord of the Rings I
Another example, from La Haine.