Unlocking Mysteries of the Parthenon

Restoration of the 2,500-year-old temple is yielding new insights into the engineering feats of the golden age’s master builders

The Parthenon, said the 19th-century French engineer Auguste Choisy, represents "the supreme effort of genius in pursuit of beauty." (Aris Messinis / AFP/ Getty Images)
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With such fanatical attention to detail, how could the Parthenon’s architects have finished the job in a mere eight or nine years, ending somewhere between 438 and 437 b.c.? (The dates come from the inscribed financial accounts.) One key factor may have been naval technology. Since the Athenians were the greatest naval power in the Aegean, they likely had unrivaled mastery of ropes, pulleys and wooden cranes. Such equipment would have facilitated the hauling and lifting of the marble blocks.

Another, counterintuitive possibility is that ancient hand tools were superior to their modern counterparts. After analyzing marks left on the marble surfaces, Korres is convinced that centuries of metallurgical experimentation enabled the ancient Athenians to create chisels and axes that were sharper and more durable than those available today. (The idea is not unprecedented. Modern metallurgists have only recently figuredout the secrets of the traditional samurai sword, which Japanese swordsmiths endowed with unrivaled sharpness and strength by regulating the amount of carbon in the steel and the temperature during forging and cooling.) Korres concludes that the ancient masons, with their superior tools, could carve marble at more than double the rate of today’s craftsmen. And the Parthenon’s original laborers had the benefit of experience, drawing on a century and a half of temple-building know-how.

Moreover, the restoration team has confronted problems that their ancient Greek counterparts could never have contemplated. During the Great Turkish War in the late 17th century—when the Ottoman Empire was battling several European countries—Greece was an occupied nation. The Turks turned the Parthenon into an ammunition dump. During a Venetian attack on Athens in 1687, a cannonball set off the Turkish munitions, blowing apartthe long walls of the Parthenon’s inner chamber. More than 700 blocks from those walls—eroded over time—now lay strewn around the Acropolis. For five years, beginning in 1997, Cathy Paraschi, a Greek-American architect on the restoration project, struggled to fit the pieces together, hunting for clues such as the shape and depth of the cuttings in the blocks that once held the ancient clamps. Eventually, she abandoned her computer database, which proved inadequate for capturing the full complexity of the puzzle. “Some days were exhilarating,” she told me, “when we finally got one piece to fit another. Other days I felt like jumping off the Acropolis.” In the end, she and her co-workers managed to identify the original positions of some 500 of the blocks. Looming over each restoration challenge is the delicate question of how far to go. Every time the workers dismantle one of Balanos’ crude fixes, it is a reminder of how destructive an overzealous restorer can be. Asthe director of the Acropolis Restoration Project, Maria Ioannidou, explains, “we’ve adopted an approach of trying to restore the maximum amount of ancient masonry while applying the minimum amount of new material.”That means using clamps and rods made of titanium—which won’t corrode and crack the marble—and soluble white cement, so that repairs can be easily undone should future generations of restorers discover a better way.

There have been some bravura feats of engineering. The 1687 explosion knocked one of the massive columns out of position and badly damaged its bottom segment. A serious earthquake in 1981 damaged it further, and theentire column appeared at risk of toppling. The obvious procedure was to dismantle the column, one segment after another, and replace the crumbling section. Korres, hoping, he said, to avoid “even the smallest departure from the column’s perfection and authenticity of construction,” designed a metal collar that exerts precisely controlled forces to grasp a column securely without harming the stone. In the early 1990s, after the careful removal of the overhead blocks and lintels, the collar was suspended by turnbuckles (adjustable connectors) inside a mounted, rectangular steel frame. By tightening the turnbuckles, the team raisedthe 55-ton column less than an inch. They then removed the bottom segment—which they repaired with fresh marble to an accuracy of one-twentieth of a millimeter—and slid it back into position. Finally, they lowered the rest of the column into place on top of the repaired segment. “It was a bold decision to do it this way,” Korres says. “But we were young and daring then.”

Perhaps none of the Parthenon’s mysteries stirs more debate than the gentle curves and inclinations engineered throughout much of its design. There is hardly a straight line to be found in the temple. Experts argue over whether these refinements were added to counter optical illusions. The eye can be tricked, for instance, into seeing an unsightly sag in flat floors built under a perched roof like the Parthenon’s. Possibly to correct this effect, the Athenians laid out the Parthenon’s base so that the 228-by-101-foot floor bulges slightly toward the middle, curving gradually upward between 4 and 4 1/2 inches on its left and right sides, and 2 1/2 inches on its front and back. One theory holds that this slight upward bulge was built simply to drain rainwater away from the temple’s interior. But that fails to explain why the same curvingprofile is repeated not only in the floor but in the entablature above the columns and in the (invisible) buried foundations. This graceful curve was clearly fundamental to the overall appearance and planning of the Parthenon.

And then there are the columns, which the Athenians built so that they bulged slightly outward at the center. This swelling was termed entasis, or tension, by Greek writers, perhaps because it makes the columns seemas if they are clenching, like a human muscle, under the weight of their load. Again, some scholars have long speculated that this design might compensate for another trick of the eye, since a row of tall, perfectlystraight-sided pillars can appear thinner at the middle than at the ends.

No matter the motivation for these refinements, many early scholars assumed that crafting such visual elements imposed tremendous extra demands on the Parthenon’s architects and masons. (One wrote of the “terrifyingcomplications” involved.) No architectural manuals survive from the Classical Greek era, but today’s experts suspect the temple builders could add curves and inclined angles with a few relatively simple surveying tricks. “If you’re building without mortar, every block...must be trimmed by hand,” notes Jim Coulton, professor emeritus of classical archaeology at Oxford University. “Although tilts and curvatures would require careful supervision by the architect, they don’t add a lot to the workload.”

Still, how could each column segment be measured so that all would fit together in a single, smoothly curving profile? The likely answer was found not in Athens but nearly 200 miles away in southwestern Turkey. In the town of Didyma rises one of the most impressive relics of the ancient world, the Temple of Apollo. Three of its 120 colossal columns still stand, each nearly twice the height of the Parthenon’s. The wealthy trading city of Miletus commissioned the temple in the age of Alexander the Great, around 150 years after completion of the Parthenon. The gigantic ruins testify to a project of grandiose ambition: it was never finished despite 600 years of construction efforts. But thanks to its unfinished state, crucial evidence was preserved on temple walls that had not yet undergone their final polishing.

A few years after the Parthenon restoration began, University of Pennsylvania scholar Lothar Haselberger was on a field trip exploring the Temple of Apollo’s innermost sanctuary. He noticed what seemed to be patterns of faint scratches on the marble walls. In the blinding morning sunlight the scratches are all but invisible, as I discovered to my initial frustration when I searched for them. After the sun had swung around and began grazing the surface, however, a delicate web of finely engraved lines started to emerge. Haselberger recalls, “All of a sudden I spotted a series of circles that corresponded precisely to the shape of a column base, the very one at the front of the temple.” He realized he had discovered the ancient equivalent of an architect’s blueprint.

Then, just above the outline of the column base, Haselberger noticed a pattern of horizontal lines with a sweeping curve inscribed along one side. Could this be related to entasis, also evident in the towering Didyma columns? After carefully plotting the pattern, the answer became clear: it was a profile view of a column with the vertical dimension—the height of the column—reduced by a factor of 16. This scale drawing must have been a key reference for the masons as they carved out one column segment after another. By measuring along the horizontal lines to the edge of the curve, they would know exactly how wide each segment would have to be to create the smooth, bulging profile. Manolis Korres believes that the ancient Athenians probably relied on a carved scale drawing similar to the one at Didyma in building the columns of the Parthenon.


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