What is a refinement?
Architects call these adjustments refinements: small departures from strict geometry, built in on purpose. The main ones on the Parthenon are the curve of the steps, the stylobate and the entablature; the entasis of the columns; the contraction of the corner intercolumniations, the spaces between the columns; and the narrowing of the metopes from the centre towards the corners. To these the building adds an almost imperceptible convergence of the columns, which lean slightly inwards. Together they lighten the heaviness of the Doric style and give the building grace and harmony.
The floor that rises
The best known refinement is under your feet. The stylobate, the top step on which the columns stand, is not level. Along the north side, 69.5 metres long, a detailed survey measured a gradual rise to a maximum of 10.3 centimetres at the centre. The same curve is repeated in the entablature above the columns, so that the whole temple is very slightly arched.
The Roman architect Vitruvius, the only ancient writer on architecture whose book survives, gives the reason. The stylobate, he writes, should be made highest in the middle, because if it is set out level it will look as if it has sunk in the centre. A long horizontal line seen from below seems to sag; a slight curve upwards makes it look straight.
Columns that swell and lean
A Doric column tapers from bottom to top, and on the Parthenon its outline is not a straight line. The shaft has entasis, the Greek word Vitruvius uses for the slight swelling made in the middle of columns: a convex curve along the shaft.
The columns of the Parthenon also lean slightly inwards. The tilt is too small to notice with the naked eye.
The trouble with corners
Corners caused two problems. The first is light: a corner column stands against the bright sky on two sides and looks thinner than the others. Vitruvius says the corner columns should be made thicker by a fiftieth of their diameter, because the open air around them eats into them visually, and on the Parthenon the four corner columns are indeed thickened.
The second problem belongs to the Doric order itself. Above the columns runs a frieze of triglyphs, the grooved blocks, alternating with metopes, the carved panels. A triglyph should sit over the centre of every column, yet at the corner of the building the last triglyph has to sit at the very end of the frieze, which leaves an awkward gap. Vitruvius explains that architects solved this by narrowing the last space between the columns, and he admits that some disliked the Doric order for temples because of it. The Parthenon’s builders narrowed the corner spaces, and they also made the metopes gradually narrower from the centre of each side towards the corners.
Why it matters
The refinements explain why no single figure tells the whole story of the measurements: almost every line of the building bends a little. They also make it hard to fit the temple to a golden ratio or any other perfect diagram, since the rectangles it seems to contain are all slightly distorted.
Where to see it
The Parthenon stands on the Acropolis of Athens. To look for the curve of the stylobate, stand at one corner and look along the north or south side with your eye close to the level of the top step. Opening hours change with the season, so check the official sites before you go.
Sources
- Acropolis Restoration Service (YSMA), “Parthenon”.
- M. Voutyras and A. Goulaki-Voutyra, Ancient Greek Art and Its Legacy, Centre for the Greek Language (2012).
- J. R. Senseney, The Art of Building in the Classical World (Cambridge University Press), appendix C, on G. P. Stevens’ survey of the north stylobate.
- Vitruvius, On Architecture 3.3.11, 3.3.13, 3.4.5 and 4.3.1-2 (LacusCurtius).
- Encyclopaedia Britannica, “Parthenon”.
