Lineas Paralelas Rojas
Saw one of my favorite optical illusions in art form:
Fabian Burgos (Argentinian b. 1962) “Lineas Paralelas Roja” (2010)
http://peano.tumblr.com/post/124384960425/abstractmodernart-fabian-burgos-argentinian-b
And needed to make it in GeoGebra.
Are the lines always parallel?