waterfall_(m_c_escher)
One of the most famous lithographies by M. C. Escher, featuring the Penrose triangle.
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