For more than 2,000 years, historians and architects have praised the Parthenon in Athens for its clever geometric design. Scholars long believed that ancient Greek architects added subtle curves to the temple's base and columns to correct optical illusions that would otherwise make the building appear to sag or warp. However, a new study by Prof Alain Goriely, a mathematician at the University of Oxford, suggests that these optical illusions are simply a myth.
By conducting detailed mathematical modelling, Prof Goriely evaluated common theories about the temple's structure. One popular claim held that the slight 6-centimetre rise in the middle of the base prevented horizontal lines from seeming to slump. Another theory suggested that the columns created a visual distortion known as the Hering illusion. Goriely found no evidence supporting the slumping effect, noting also that the marble columns are far too vertical to trigger the Hering illusion in 3D space. Similarly, the 18-millimetre bulge in the columns, known as entasis, is virtually imperceptible from typical viewing distances.
Goriely traced the origin of the myth to Vitruvius, a Roman architect who wrote about the Parthenon four centuries after its construction. Vitruvius’s account was widely copied into architectural textbooks and remains popular today, even appearing in AI chatbot outputs. Goriely proposes that the Parthenon's architectural features had far more practical or aesthetic motives: the curved base likely prevented rainwater from pooling, while the gentle curves of the columns may have simply looked more organic and pleasing to ancient Greeks.
Unusually for an academic study published in Royal Society Open Science, Goriely ends by encouraging readers to trust their own eyes and evaluate architecture for themselves. Responding to the study, Prof Frank Salmon, a Cambridge historian of classical architecture, noted that experts have long been cautious of Vitruvius’s explanations, given the gap of several centuries and the loss of original Greek texts from that era.