The Ames Room

An Ames room is a distorted room that is used to create an optical illusion. It was invented by American ophthalmologist Adelbert Ames in 1946 based on a concept by Hermann Helmholtz.

An Ames room is constructed so that from the front it appears to be an ordinary cubic-shaped room, with a back wall and two side walls perpendicular to each other and perpendicular to the horizontally level floor and ceiling. However, this is a trick of perspective and the true shape of the room is trapezoidal.

As a result of the optical illusion, a person standing in one corner appears to the observer to be a giant, while a person standing in the other corner appears to be a dwarf. The illusion is convincing enough that a person walking back and forth from the left corner to the right corner appears to grow or shrink.

Here's a video of an Ames Room.