In Wolfram MathWorld we find a survey with many references to optical illusions and impossible figures.
Benham's Wheel , Black Dot Illusion ,Bullseye Illusion , Café Wall Illusion , Freemish Crate , Goblet Illusion ,Hermann Grid Illusion ,Hermann-Hering Illusion ,Hyzer's Illusion , Impossible Figure , Irradiation Illusion , Kanizsa Triangle ,Müller-Lyer Illusion ,Necker Cube , Orbison's Illusion , Parallelogram Illusion , Penrose Stairway ,Poggendorff Illusion , Ponzo's Illusion , Rabbit-Duck Illusion , Tribar ,Tribox , Vertical-Horizontal Illusion , Young Girl-Old Woman Illusion , Zöllner's Illusion . [Pages Linking Here]
Freemish Crate
The Freemish crate, also called Escher's cube (Elber) or Hyzer's illusion (Pappas 1989, p. 13), is an impossible figure box that can be drawn but not built Ambihelical Hexnut , Freemish Crate , Home Plate , Illusion , Impossible Fork , Impossible Joinery ,Impossible Torus , Klein Bottle , Necker Cube , Penrose Stairway ,Penrose Triangle , Tribar , Tribox .[Pages Linking Here]