Imagine walking down the street when suddenly you come up to a gaping hole that causes you to stop in your tracks. If you take another step, it’s an inevitable plunge. Or is it? Sidewalk illusions are everywhere these days, but it wasn’t always that way. Here’s how the art form came to be, and the tricks artists use to make a 2-D surface look 3-D. Press play to see how an ordinary sidewalk can be transformed into a completely different scene.