The Bent Pencil
This drawing of two rings and a pencil is impossible unless you believe that the pencil is made of rubber. However, for this purpose assume the pencil is normal. It cannot bend in the way shown without breaking.
This cartoon poster uses the impossible staircase design to illustrate the futility of up-and-coming climbers in the corporate world. The faster you go the farther behind you get.
These 3 Gears could Orient not.
An impossible gear ratio. Each gear is complete in itself, but requires parts of its companions to exist. Look closely at how these 3 gears mesh.
Each gear needs a geometric piece of its neighbor to complete itself. So the whole scene is impossible from the get go. It could never happen this way in real life. However the ensemble lives quite happily in 2D, made to look 3D.
Impossible Hollow Hexagon
This impossible figure resembles a mobius strip. If you follow any surface around the desgin, the inside will eventually become the outside.
This elegant design is really an impossible square that has been shaped into a circle. If you trace any surface around the figure you will travel from the inside to the outside.
The Impossible Square
A simple square made impossible by artistry, and a complete disregard for the laws of perspective.
See also cover of a 2009 sketchbook calendar by Robert Ausbourne.
Images were found at