3D art is often deployed as a bit of a gimmick, whether it's adorning the floors of shopping centres or scaring people walking into lifts.
But what if a 3D optical illusion was painted on a grand scale, so that it changed the area it appeared in completely?
Eric Grohe is a muralist who takes months over each project, transforming ugly walls in run down areas into epic, immersive pictures.
What we like best about Grohe's work is the escapism it offers. Walk down any run down town or unforgiving city he's passed through and there they are, glimpses into better worlds, where renaissance architecture frames pastoral idylls and we can imagine, if only fleetingly, dropping everything and walking straight into them.
And if the hit-and-run style of British street artists like Banksy offers the thrill of one day stumbling upon a new creation, Grohe's work offers up the complete opposite: residents get to walk by and see his work unfold piece by piece every day until eventually it is complete.
Born in New York in 1944, Grohe became a professional graphic designer and illustrator in Seattle and served briefly in Vietnam. He then spent time in the UK, working with the Cambridge University archaeology department. He has worked as an illustrator in France, Greece, Israel and England as well as the US.
To see what Grohe's urban canvases look like before, during and after his work, check out the mind-blowing gallery below.