A simple mathematical model of a two-dimensional universe, called the Poincaré Upper Halfplane, illustrates the possibility of a universe with an unattainable edge. In this article, I describe this model -a famous example of a noneuclidean geometry-and explain how conversations with an analytic number theorist led me to create wallpaper patterns for its inhabitants. These are interesting not only for their high "Gee whiz!"factor, but also as a window for observing the features of this unusual geometry.