What Does a Circle Look Like?

We're used to a standard kind of geometry, but there are other geometries. If you define the distance between two points in a plane as in the number of units north south plus the number of Units east west, right? You can define a distance like that. It's not the euclidean distance because you're not allowed to take diagonal paths in this geometry. The set of all points three blocks away from a given point is an interesting question. Try to picture that in your head.