Optical refinements: entasis and stylobate curvature
Refinamientos ópticos: éntasis y curvatura del estilóbato
- Date
- 447-432 BCE · confidence medium
- Place
- Athens, Attica, Greece
- Credited to
- Iktinos and Kallikrates (architects of the Parthenon)
- Field
- Tools
⚠️ Disputed: the sources disagree.
What it is
The Parthenon's architects slightly curved the platform and swelled the shafts with entasis to correct the illusion that straight lines sag or thin out. Every block had to be cut for a unique position, to millimetre precision.
Curvature and entasis already appear in Archaic temples (Paestum, Corinth, 6th century BC). That they aimed at optical correction is an interpretation, first measured systematically by Penrose in 1851.
What it led to
- treatises on proportion and optical correction in classical architecture
- masonry workshops using templates and assembly marks
- a debate on sight and architecture that reaches Vitruvius