 In part because of the ritual secrecy of such inner spaces, it is not known exactly what took place within opisthodomoi; it can safely be assumed that practice varied widely by place, date and particular temple.Architecturally, the opisthodomos (as a back room) balances the pronaos or porch of a temple, creating a plan with diaxial symmetry.The upper portion of its outer wall could be decorated with a frieze, as on the Hephaisteion and the Parthenon.