The article is an analysis of meaningful spatial effects of the decoration in the Galerie des glaces at Versailles. Visual spaces (representational space, reflected space of the mirrors, and the physiacal space of the room and the site) are examined in terms of their interrelations and in terms of address to a viewer. Visual space is considered the most important tool to arouse curiosity and admiration in the spectator, the rhetorically most efficient aspect of the decoration. Three types of effects are discerned and discussed: ambiguity; control and domination; tension (as intensification, as challenge, and as risk).