This study reveals the crucial role played by sacred geometry in the spatial structure of Velázquez's Las Meninas . It further explains how Velázquez, by means of geometric composition, achieved double centrality and why nearly half of those who look at his masterpiece perceive that the point of view is opposite the mirror. The spatial analysis of the floor plan confirms that, according to the law of reflection, the image in the mirror is coming from the large canvas. The correct floor plan follows from the Renaissance perspective system, and its understanding leads to further revelation of its universal use.