All 12 of the Parthenon's claimed optical corrections fail an Oxford mathematician's audit
Alain Goriely worked through the refinements one at a time and found that either nobody has demonstrated the illusion or the effect is too small to see, and the earliest claim of intent postdates the temple by 400 years.
The Scientist · Science desk
What happened
- A mathematician at the University of Oxford, Alain Goriely, went through 12 proposed optical corrections in the Parthenon and found each one either unsupported by evidence or too small to be perceptible under typical viewing conditions.
- The largest claim covers the upward curve at the middle of the stylobate and the entablature, held to stop those horizontals looking as though they sag, and Goriely calculates that a viewer would perceive no sagging.
- Also on the list are the slight bulge at mid-height of the columns, said to stop them looking pinched, and the thicker corner columns, said to offset the stronger light at the building's edges.
- The competing explanation for the curve, that its small gradients drain water and stop puddles forming, was put forward long ago and dismissed in the 1800s.
Why it matters
- What it sets up precedent The same upward curve appears in other Greek temples, so the standard of evidence applied here is now available wherever that curve is read as a deliberate correction.
- What it limits constraint A calculation can show that an illusion does not occur without showing what the builders wanted, and Goriely says the thinking behind the construction cannot be known definitively.
- What doesn't add up contradiction Goriely says the illusion story was never universally accepted among experts even as it became the standard account, which makes the consensus a weaker thing to cite than its ubiquity suggests.
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An optical-correction claim has two halves that can be checked separately: the deviation cut into the stone, and the perceptual error it is supposed to cancel. The deviations are not in dispute. The temple is 69.5 metres long and 30.9 metres wide, and although it appears straight it has almost no straight lines or right angles [2]. The standing hypothesis is that the builders expected straight lines to look curved, so they built curves to make the building look straight [3].
Goriely, at the University of Oxford, said it is widely accepted that the temple was made this way on purpose, but that there is strictly no evidence the refinements in the Parthenon actually produce the proposed visual illusions [4]. His objection concerns what happens when a two-dimensional argument is worked out in three dimensions with a viewer in it. "There are certain effects such as the Hering illusion that, on paper, would give qualitatively the same direction of effect, but if you actually do the computation, you realise that the effect does not appear," he said. "And although it might work on paper, the effect in the real 3D building with an observer is completely different." [8]
For the columns, the record is thinner still. Goriely says no pinching illusion has ever been scientifically demonstrated, even in controlled tests using three-dimensional reconstructions of temples [13]. His alternatives are mundane: builders may have thought curved columns more pleasing than straight ones, curvature improves resistance to buckling, and a corner column carries a slightly heavier load [14]. "If the columns do get narrower at the top, that could be to make them seem taller, or just because, for stability, one wants a base thicker than the top," said Marge Livingstone, a neuroscientist at Harvard Medical School who studies visual perception [15].
Livingstone also said of the curved floor: "I think it must have been for drainage, just like on roads." [11] The surface at issue is large. The 69.5 by 30.9 metre plan works out at a footprint of about 2,150 square metres [23]. John Senseney at the University of Arizona in Tucson puts the cause in the building process, saying the curvature throughout the building is a consequence of the curve of the platform on which it was built [19]. "The refinement of convex curvature is an extraordinarily sophisticated product of the expert knowledge, judgement, tools and techniques of common and, often, enslaved labourers working collaboratively on site," he said, adding that the curvature "is not a product of an intended optical correction" [20].
The earliest surviving statement of intent is not Greek. Goriely says the first mentions of the Parthenon being designed with optical illusions in mind come from Vitruvius's De architectura, written some 400 years after the temple [17]. Since the building went up in the 5th century BC [1], that dates the claim to roughly the first century BC [22]. Ancient Greeks knew visual illusions existed, Goriely says, but there is no evidence they built the Parthenon to counteract the ones usually cited [16].
The calculation is about the effect. Whether the builders were aiming at an illusion is a separate question, and one no computation can reach, because a refinement can be deliberate and still fail to do what its maker hoped. Goriely says the ideas took hold so strongly because they capture the imagination [21]. The New Scientist report does not name a journal for the analysis or the viewing distances it assumes [18].
What to watch
- Whether the calculations appear in a peer-reviewed venue with the assumed viewing distances and perceptual thresholds stated.
- A controlled perceptual test with human observers and three-dimensional temple reconstructions that either shows the pinching illusion or does not.
- A measurement of how much water the stylobate gradients actually shed, which would put the drainage account on evidence.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence62
- Adoption
- Not scored
- Hype gap+15
- Incentives
- Not scored
- Confidence60
Claim ledger
Ranked by verification strength, evidence, and original report placement.
- [1]
The Parthenon was built in the 5th century BC in Athens and is considered the culmination of the Doric style of classical Greek architecture.
- [2]
The Parthenon is 69.5 metres long and 30.9 metres wide and, although appearing straight, famously has almost no straight lines or right angles.
- [3]
The enduring hypothesis is that the Parthenon was built with refinements to counteract visual illusions a viewer would experience: builders thought straight lines would look curved, so they built it curved to make it look straight.
- [4]
Alain Goriely at the University of Oxford said: "It's widely accepted that it was made this way on purpose. But there is strictly no evidence that the refinements in the Parthenon actually produce the proposed visual illusions."
- [5]
Goriely, a mathematician at the University of Oxford, examined 12 proposed optical corrections in the Parthenon and found that they are either unsupported by evidence or too small to have a perceptible effect under typical viewing conditions.
- [6]
The biggest illusion claim is that the upward curve in the middle of many horizontal elements, also seen in other temples, exists so the elements do not look as if they sag; it covers the stylobate, the stepped base on which the columns stand, and the horizontal entablature across the tops of the columns.
- [7]
Goriely calculates that viewers would not perceive any sagging, so the anti-sagging illusion does not stand up.
- [8]
Goriely said: "There are certain effects such as the Hering illusion that, on paper, would give qualitatively the same direction of effect, but if you actually do the computation, you realise that the effect does not appear. And although it might work on paper, the effect in the real 3D building with an observer is completely different."
- [9]
A more likely reason for the curve, put forward before but dismissed in the 1800s, is that the small gradients help water drain away and prevent puddles forming.
- [10]
Goriely says we cannot know definitively what the thinking was behind the construction.
- [11]
Marge Livingstone, a neuroscientist who studies visual perception at Harvard Medical School, does not think the floor was curved to create an illusion and said: "I think it must have been for drainage, just like on roads."
- [12]
Other proposed illusions are that the columns have a slight bulge in their middles to prevent them appearing pinched, and that the corner columns were made thicker than the internal ones to offset the stronger light around the edges that would make them seem thinner.
- [13]
Goriely thinks no such pinching illusion has ever been scientifically demonstrated, even in controlled tests using three-dimensional reconstructions of temples.
- [14]
Goriely says simpler explanations for the column shapes could be that builders believed curved columns look more pleasing than straight ones, or that the shaping improves resistance against buckling, and that corner columns could be bigger because they carry a slightly heavier load.
- [15]
Livingstone said: "If the columns do get narrower at the top, that could be to make them seem taller, or just because, for stability, one wants a base thicker than the top."
- [16]
Ancient Greeks were aware of the existence of visual illusions, but Goriely says there is no evidence they made the Parthenon to counteract the ones often cited.
- [17]
Goriely says the first mentions of the Parthenon being designed with optical illusions in mind come from Vitruvius's De architectura, written some 400 years after the temple was built.
- [18]
The New Scientist report does not name a journal or publication venue for Goriely's analysis, nor the viewing distances it assumes.
- [19]
John Senseney at the University of Arizona in Tucson says the curvature throughout the building is a consequence of the curve of the platform on which it was built.
- [20]
Senseney said: "The refinement of convex curvature is an extraordinarily sophisticated product of the expert knowledge, judgement, tools and techniques of common and, often, enslaved labourers working collaboratively on site. It is not a product of an elite architect's mathematical prowess created abstractly and then executed by the builders. And this curvature is not a product of an intended optical correction."
- [21]
Goriely says the ideas have taken hold so strongly because they capture the imagination.
- [22]
Vitruvius's account, written some 400 years after a 5th-century BC building, dates to roughly the first century BC.
- [23]
The Parthenon's plan of 69.5 metres by 30.9 metres gives a footprint of about 2,150 square metres.
- [24]
Goriely says the myths about the Parthenon's optical corrections have never been universally accepted among experts.
Sources
2 independent publishers whose own reporting we read for this story.
- newscientist.comThe Parthenon’s architectural illusions are a myth
1 article · September 15, 2026
- phys.orgMathematician challenges a 2,000-year-old legend about the Parthenon's optical illusions
1 article · September 16, 2026
Topics and entities
Topics
- Visual perception
- Classical architecture
Entities
- Royal Society Open Science
- University of Oxford
- Marge Livingstone