How Was Stonehenge Built?
Stonehenge was built in the late Stone Age, between 4,000 and 5,000 years ago, around the same time as the Pyramids of Egypt.
Since then, much of Stonehenge has been eroded, collapsed, sunken by earthworms, or pilfered by tourists wanting elaborate garden features. What we see on the Salisbury Plains today are the partial remains.
What Did Stonehenge Look Like Originally?
There's a little guesswork to visualising the original Stonehenge, but here's a likely scenario:
Stonehenge isn't even the biggest henge in Britain. That award goes to Marden Henge in Wiltshire, whose 40-acre earthworks make it ten times larger.
But Stonehenge is the most architecturally sophisticated, made famous for being the only surviving lintelled stone circle, which I don't need to tell you means it has horizontal blocks.
Who Built Stonehenge?
I'm afraid it wasn't the Druids. Carbon dating has found Stonehenge was built a good 1,000 years before the Celts and their learned caste of high priests arrived in Britain. However, this doesn't stop people who identify as modern Druids from gathering at Stonehenge for the summer solstice each year.
Instead, many historians now agree that Stonehenge was built originally by Neolithic farmers who came to Britain from Anatolia (now Turkey) some 6,000 years ago. This was part of a much larger migration that introduced farming to hunter-gatherers across Europe. They also brought with them a penchant for large stone monuments.
Yet DNA evidence suggests little mixing took place between the migrant farmers and the British hunter-gatherers. The farmers who made it to Britain were relatively small in number and left virtually no genetic legacy behind.
In fact, about 1,500 years after their arrival in Britain, they were replaced entirely by a new population from the Netherlands called the Beaker People. The genetic shift was so rapid that some historians point to an invasion. With Stonehenge unfinished, it's likely the Beaker People built the largest circle of outer stones, which are dated much later than the original construction.
Archaeologists have unearthed polished Stone Age tools at Stonehenge, as well as human remains which suggest it was originally a burial site. In the millennia that followed, Stonehenge was adopted by the Beaker People and likely served as a ceremonial hub and a destination for religious pilgrimage.
Astronomers have long suggested there's a cosmic significance to the arrangement of Stonehenge. Some of the stones appear aligned with recurring astronomical phenomena like solstices, equinoxes, and eclipses. However, this hypothesis may be reaching: history suggests the Neolithic tribes didn't have the cosmological knowledge nor the mathematics to predict these kinds of events.
How Was Stonehenge Built?
Remarkably, Stonehenge was built in three major phases, expanded and updated by separate populations over 1,000 years. The upside of such a prolonged construction is that nobody at the start of the project was still alive to complain about delays at the end.
Phase I: The Aubrey Holes - Dug 5,000 Years Ago
The original earthworks began in 3000 BCE when Stone Age builders used picks made from deer antlers to create a massive ditch, a bank, and fifty large holes now known as the Aubrey Holes.
The Aubrey Holes may have provided the foundations for a wooden construction of some kind; a wood henge. But there were no stone monuments at this point. Still, any ring-shaped bank and ditch made during the Neolithic period qualifies as a henge, with stone monuments serving as a bonus feature.
Early Stonehenge was a burial ground for the elite, whose bodies were interred over 200 years. Although many of them were cremated, the ashes still contain strontium isotopes, allowing researchers to conclude that many of the deceased actually lived for some time in Wales, more than 225 km (140 miles) away.
Phase II: The Bluestones - Added 4,500 Years Ago
The nearest hardware shop must have been busy, or closed, or not invented, because it was 500 years before they performed an upgrade.
Around 2500 BCE, workers brought in 82 bluestones weighing 3,500 kg (7,700 lb) each, carved out from the Preseli Hills in Wales.
It's likely the stones were shipped along waterways, then rolled on logs like a conveyor belt across the land. With steady mental and physical leverage, the stones were heaved into two concentric semi-circles.
No-one knows why the Welsh inhabitants wanted to be buried far away in the South of England, nor why they brought half the local lithosphere with them. But by Jove that's what they did.
Phase III: The Sarsen Stones - Added 4,000 Years Ago
The final build was completed another 500 years later, in 2000 BCE, when the Beaker People had replaced the original Stonehenge populations and decided to tinker around with their arrangement. And by tinker I mean perform a massive overhaul.
The new Stonehenge builders got to work with 30 sarsen stones weighing 22,000 kg (50,000 lbs) each. That's about five male elephants per stone, if you prefer your measurements in elephants.
The sarsen stones came from the Marlborough Downs, 32 km (20 miles) away from Stonehenge. What really takes the biscuit is that they did this before the invention of the Bronze Age wheel.
For a long time, it was thought that Stonehenge was built by hundreds, if not thousands, of coordinated workers. But with the correct application of physics, it may have been possible with a relatively small team of skilled workers.
Here's retired builder, Wally Wallington, performing an extraordinary demonstration of how he moves massive concrete blocks. He does it all singlehandedly, with just wood and stone tools and a fair deal of mechanical intuition.
Surprisingly, the second-wave builders of Stonehenge used woodwork joinery techniques to lock the stones in place. These included protruding tenons, mortice holes, and good old tongue-and-groove joinery.
And there Stonehenge stood, for another 4,000 years, to the present day. The largest surviving sarsen stone is 8.7 metres tall, a third of which is now underground. Charles Darwin blamed the vigorous bioturbation habits of earthworms causing the stones to sink.
Visitors to Stonehenge can walk around the monument, and even get special access to the Inner Circle, but tourists aren't allowed to touch the stones. And don't even think about souvenir hunting among the ruins. There is, of course, a gift shop for that.
Research is ongoing at Stonehenge. Ground-penetrating radar, magnetometers, and other 3D mapping technologies are generating piles of new data on the stones and the bones. In the process, previously unknown henges have been discovered in the surrounding countryside, along with more clues as to why Stonehenge was built in the first place.
And yet, without some time-dilating window on the past, we'll never know definitively how Stonehenge was built, nor why henges were so very important to the religious journeys of various Neolithic cultures.
"Those vast stones, standing in concentric rings in the middle of a basin on Salisbury Plain, carefully placed by who-knows-who thousands of years ago, must mean something. But nobody can tell us what. Not exactly. The clues that remain will always prove insufficient to our curiosity. Each archaeological advance yields more questions, and more theories to be tested. Our ignorance shrinks by fractions. What we know is always dwarfed by what we can never know." - Ed Caeser, The Smithsonian