  Primarily having emerged from a topological question, Jankins-Neumann
ziggurat also appears in the theory of dynamical systems on the circle. It
describes an answer to the following question: given the rotation numbers of
two orientation-preserving circle homeomorphisms, what can be said about the
rotation number of their composition? In this paper, we consider a formula,
proved by Calegari and Walker, as definition of ziggurat. Using it, we
establish its self-similarity. Also, we propose a short proof of equivalence
between Calegary-Walker and Jankins-Neumann's descriptions of the ziggurat.
