A longstanding belief regarding the architectural design of the Parthenon, the ancient Greek temple on the Acropolis in Athens, has been called into question by new mathematical analysis. Professor Alain Goriely of the University of Oxford conducted a detailed study of the optical illusions purportedly addressed by the Parthenon’s subtle curves and found little evidence supporting the idea that these adjustments were intended to correct visual distortions.

For more than two millennia, scholars and architects have admired the Parthenon’s design, attributing its slight architectural curves to deliberate optical refinements. According to traditional accounts, most notably those dating back to the 1st-century Roman architect Vitruvius, the temple’s stylobate—the base platform—was slightly arched to counteract an illusion that would otherwise cause it to appear sagging in the middle. This narrative also includes claims that the columns’ distinct bulging shape, or entasis, was designed to prevent them from seeming narrower at their midpoint.

However, Goriely’s research, which involved extensive mathematical modeling, challenges these assumptions. He found no convincing evidence for the alleged sagging illusion of horizontal lines or for the common explanation that the temple’s fluted columns produce a visual effect similar to the Hering illusion—an optical phenomenon where parallel lines appear bowed due to intersecting lines placed at acute angles. Since the Parthenon’s columns stand nearly vertical, he argues they are unlikely to create such illusions, especially in three-dimensional form.

Furthermore, the minimal curvature of the columns—about 18 millimeters—appears too subtle to significantly affect perception at typical viewing distances. Goriely’s analysis extends to other claimed “optical corrections,” many of which he also discounts as lacking a perceptible impact or definitive proof.

In his paper published in Royal Society Open Science, Goriely suggests alternative explanations for the Parthenon’s architectural choices. The slight arch in the stylobate may have served a practical purpose, such as facilitating water drainage. Similarly, the curvature in the columns could have been intended to evoke a more natural, aesthetically pleasing form rather than address visual illusions.

Tracing the origin of these beliefs, Goriely points to Vitruvius’s writings as the likely source of the myth, which has since become entrenched in architectural history and popular culture. The narrative remains widespread, even echoed by modern artificial intelligence tools. Goriely characterizes it as perhaps one of the oldest myths aside from those rooted in religion.

While this study provides a reassessment of long-accepted views about the Parthenon’s design, the reasons behind its architectural refinements remain a subject for further exploration.