A German street artist, who is known under his moniker 1010, has created some rather unique artworks on the walls of buildings. The look is achieved through a process involving layering the various colours to give the illusion of depth in the artworks.
There colourful works of art have helped dress up many a boring building, guying the look of some sort of tunnel or portal to an unknown universe. A great uses of optical illusions, it tricks the mind into thinking the image goes inwards, as opposed to just a simple painting. You can check out more of the artists work at Juxtapoz or Facebook.