One of the most famous lithographies by M. C. Escher, featuring the Penrose triangle.

h4. See also

* http://en.wikipedia.org/wiki/Waterfall_%28M._C._Escher%29
* http://en.wikipedia.org/wiki/M._C._Escher
* http://en.wikipedia.org/wiki/Penrose_triangle
waterfall (m c escher)