Yeah, I’ve stumbled onto a few of those! In Mexico City there’s this old colonial wall in the Centro that’s covered in graffiti that actually responds to the people walking past – the words shift with the light, almost like a living story. In Berlin, on a quiet side street, a concrete wall is painted with a giant “Hello” that changes colors when you touch it, and the local kids always laugh when the letters shout back in bright neon. I’ve also seen a little mural in Barcelona where the faces of tourists appear to be talking back when you look at them from the right angle. It’s like the city itself is gossiping with you!