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The secret plans of ancient architects

Blueprints for ancient Greek temples like the Parthenon have been under the archaeologists' noses for thousands of years, writes Dr Karl Kruszelnicki.

For thousands of years, people have looked on the ancient Greek temples (like the Parthenon) in awe of their perfection in design and construction. Architects have known for centuries that they were built with deliberate mistakes that somehow made them look more perfect. At what stage in the building process did they decide to put in the subtle mistakes? We could find out, if only we could get hold of the original plans. But everybody knew that there was no chance of ever finding them. But everybody was wrong. The blueprints have been under the archaeologists' noses for thousands of years.

The secret was found at the ruined temple of Apollo at Didyma. Apollo was the Greek god of light, art and prophecy. The Greeks started building this magnificent temple shortly after Alexander the Great arrived in Asia Minor in 334 BC. But work went on at a snail's pace, and the temple wasn't finished when work finally ground to a halt after about 6 centuries, around 300 AD. There was no more work done on the half-finished shell of the temple until the 1500s, when an earthquake knocked over much of what had already been built.

But there's enough left to show that the temple of Apollo is magnificent, even as a ruin. There's a huge platform, about 4 metres high, 120 metres long, and 60 metres wide. It's the size of eight Olympic Swimming Pools, stacked side-by-side. Originally there were going to be 108 columns, each of them about 20 metres tall, but only three of them still stand.

But where were the blueprints or plans?

The big breakthrough came in October 1979, when Lothar Haselberger, an archaeologist from the Technical University of Munich, was wandering through the ruined temple, and found the original construction plans. He happened to see dozens of very thin, very shallow lines that were scratched into the marble of some of the lower walls.

It was the first time he'd seen these lines, and yet he had walked past this point dozens of times. He stopped in amazement, and as he watched, the Sun moved a tiny amount, and the lines faded back into the white marble and vanished. These were the missing construction plans. He came back day after day to look closely at the other walls of the temple, to catch the different light and shadows as the Sun moved through the sky.

He found more straight lines, and circles and quarter circles, and even more complicated shapes. The lines were as thin as a pencil mark, and were cut about half a millimetre deep into the surface of the marble. In some places they had been washed away by thousands of years of rainwater. In other places, they were covered by sinter, a thin mineral deposit that is left behind when water evaporates away. But surprisingly, most of the lines were still visible after thousands of years in the open.

Lothar began to copy the lines onto paper. He found that they had been done so accurately, they could have been done only by experienced draftpersons. He realised that the blueprint, from which the temple was built, was drawn into the very stone of the temple. The surface area of the plans was huge, covering hundreds of square metres. On the plans, you can still see where some of the designs were changed. Most of the etchings are done full life-size. Because the columns are about 20 metres tall, they were drawn lying on their side. The designers drew only half of each column, because the other half was an exact mirror image. He noticed something special about the drawings of the columns - the subtle and deliberate mistakes.

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Better than perfect

The columns did not have parallel sides. Instead, they bulged out by exactly 4.65 cm, and then tapered in again near the top. The giant platform (60 metres by 120 metres) that the columns were to be mounted on was not dead flat either. It bulged upwards in the middle by about 11 cm.

On the plans carved into the stone, we can still see how they incorporated these deliberate mistakes. To make a complicated shape (like the base of a column) they drew various combinations of straight lines that they then divided into thirds. And then they put circles of many different sizes together and combined them with the various cut lines. This got them close to the final shape.

And then we can see how, right at the very end, they abandoned strict geometry, and added a bit of the personal human touch. The unknown architect drew in freely, by hand, a slightly different curve. So while the architects started off with the strict rules of geometry, they would go beyond them whenever they felt the aesthetics of the building needed it. The Greeks called this slight imperfection "entasis", or "tension".

Once it was realised that the plans for these temples were inscribed into their bases, the archaeological world went looking. They found similar plans inscribed on the temple of Athena (in Priene) and the temple of Artemis (at Sardis). Practically all of the plans on the floors were gone, because they had been built over and had vanished, as rocks were built on top of them. And as for the plans on the walls - once the temple was finished, the final stage was to polish off about half a millimetre of rock. However, the temple of Apollo was abandoned before they got around to this polishing.

This idea of inscribing the plans into the rocks of the buildings is a really neat idea. It would take many lifetimes to build a temple. If the plans were scratched into the marble, later workers could follow the original plan of someone who had been dead for many centuries.

But the Greeks weren't the first. The archaeologists then found out that Egyptian architects had used the same techniques some 2,000 years before the Greeks. And more recently, the Romans, and even more recently, the builders of the medieval cathedrals, used the same technique. These construction plans have been found scratched into the walls and floors of Cathedrals at York, Chartres and Reims. The mystery of the missing plans had been solved - they had been under their feet all the time.

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Expensive Temple

From the book-keeping records that we have from other sources in Greek history, we know that each column cost about 40,000 drachmas, or over a million of today's dollars. There were more than 120 columns needed for the temple of Apollo. So just the columns alone would have cost about half the cost of the Sydney Opera House, or about three F-18 fighter planes. It probably would have been as much again for the rest of the temple. Such a temple was definitely a major undertaking.

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Notes

This is an extract from Dr Karl's book Bizarre Moments in Science, ISBN 0 7333 0210 6.

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