Ames Room

LINK quote [Why do the two identical twins in this room appear to be drastically different in size? The distorted room seen above is named after the American ophthalmologist Adelbert Ames, Jr., who first constructed such a room in 1946. He based his design on a concept originally conceived by Hermann Helmholtz in the late 19th century. There are two illusions associated with the Ames Room. First the room appears cubic when viewed monocularly from a special viewing point (the true shape of the room is trapezoidal). Secondly, within an Ames Room people or objects can appear to grow or shrink when moving from one corner to the other].
(via Geisha asobi blog)