In 1954 the artist M.C. Escher and the mathematician H. S. M. Coxeter met in Amsterdam and a decades long friendship and collaboration began. We will explore Escher's art and see how communication with Coxeter influenced his work. We will also see how Escher's art led Coxeter to explore geometric concepts. Along the way we will learn about hyperbolic geometry and discuss tessellation in Euclidean and non-Euclidean geometries.