Do not trust your eyes and do not believe what you see – painters are, after all, the greatest deceivers! Above all, illusionist painting aims to deceive the eye of the beholder. Although the picture surface is two-dimensional, it suggests openings to the inside and outside. It provides views into vast illusory worlds, things and beings emerge from the picture and conquer the viewer’s space. Reality and fiction interpenetrate in an amazing way. Today, digital artists achieve such effects with breathtaking perfection. Similar goals were already pursued by their painting colleagues in antiquity. The lecture shows which tricks were used then and now to mislead the viewer’s eye and create so-called trompe-l’œils. We start with works of art from antiquity and end with the so-called parallax effect, an interactive effect in web design.