What is one of the optical refinements used in the Parthenon?

The Parthenon is renowned for its use of optical refinements that enhance its aesthetic appeal and visual harmony. One significant refinement is column curvature, often referred to as entasis. This design technique involves slightly bulging the columns as they rise, creating the illusion of strength and elegance. In its sheer height, the slight curvature counteracts the visual perception that a perfectly straight column might appear to sag; it adds vitality to the structure and draws the eye upward, emphasizing its grandeur.

While a flat stylobate could suggest a sense of stability, it does not possess the same optical effect or refinement as column curvature. Metallic elements and brick materials are less about visual enhancements in the context of the Parthenon’s architecture, focusing instead on construction techniques or materials rather than optical manipulation. Column curvature stands out specifically for its influence on the viewer's experience of the building and its stylistic sophistication.