Even if you don't know much about ancient history and prehistoric monuments, you've probably heard of Stonehenge. The history of this incredible structure dates back more than 5,000 years, and while it was certainly important to the people who built it, those architects would have had no way of knowing that their creation would become world-famous. Nowadays, Stonehenge is featured everywhere, from famous films to your friends' holiday photos. But if there's one thing everyone seems to know about Stonehenge... it's that there's a lot no one seems to know about Stonehenge. The monument is surrounded by notoriously perplexing questions: Who built it? What was it for? Who is buried underneath? And above all: how did the ancients move and erect those enormous stones? Many explanations have been proposed over the years, including lost technologies, pure magic, and, of course, aliens. But while speculation is fun and all, Stonehenge doesn't need the help of myths and legends to be cool. After all, just because you understand something doesn't make it any less fascinating - and there's a lot about Stonehenge that we understand. We say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essay Archaeologists have intensively studied this structure for more than a century, and while many mysteries still remain, modern science has taught us quite a bit. For centuries, visitors to Salisbury Plain in Wiltshire, England, have marveled at Stonehenge and tried to guess the identity of its builders. One of the first written suggestions came from Geoffrey of Monmouth, a bishop famous for his imaginative writings on British history. In 1100 he claimed that the monument had been built by Merlin. Yes. The wizard Merlin, from Arthurian legend. The story goes that Merlin used magic to build Stonehenge as a monument to fallen soldiers, using huge rocks originally brought out of Africa by giants. And for a while this was actually quite a popular story. Later scholars became more realistic and proposed a list of non-fictitious suspects, including the Romans and the Mycenaeans of Greece. And while artifacts found at Stonehenge indicate that some of those cultures used or visited the monument in its final years, recent evidence has ruled out that they were its builders. Much of this evidence comes from radiocarbon dating. This method is one of the most useful tools available to archaeologists, because in most cases it only requires radioactive carbon. In nature, carbon atoms come in different forms, or isotopes, which have different numbers of neutrons. Some of these isotopes, like the key one called carbon-14, are radioactive, so they break down over time at very predictable rates. By calculating the amount of decayed radioactive carbon in a material, scientists can calculate how long ago the material formed. This means they can date any type of organic substance. Including those found at Stonehenge. Radiocarbon dating of human remains and artifacts has revealed that the monument's history actually dates back to around 3000 BC. Which is far too old to have been built by the Romans or the Mycenaeans... or by Merlin! Unfortunately, whatever group created Stonehenge didn't leave much evidence about who they were, so their identity remains a mystery. And the story is complicated even further by the fact that, like many ancient monuments, Stonehenge wasn't built in a day... or even a century. Archaeologists have identified multiple phases of construction at the site over a period of around 1500 years, probably by different groups ofpeople. The first construction took place about 5000 years ago and involved the excavation of the circular moat which still surrounds the monument. This formation is very similar to a type of embankment called a henge. We know this in part from carbon dating pieces of the abandoned instruments. But we also found cremated human remains from this period, hidden in pits within the Henge. It's possible that some of the first stones were also erected around this time, but based on other evidence, it's very likely that the famous giant stones didn't arrive for another 500 years. So while there isn't enough evidence to say exactly who did the heavy lifting, archeology has been able to help us figure out when it happened, ruling out some suspects. Science has also been able to help us understand how Stonehenge was built. And one thing is for sure: putting all these rocks in their place was no easy task. There are two main categories of stones – also called megaliths – at Stonehenge. Huge sarsens typically weigh around 22 tons each, while smaller bluestones weigh 2 to 5 tons. Today there are about three dozen stones at the site, arranged in two outer circles and two inner horseshoes. But based on the holes dug in the ground, there were probably more. From what we can tell, the workers first dug holes into which to insert the rocks and then lifted them upright, probably with the help of ropes, A-frames and lots and lots of people. The standing stones were then capped with horizontal beams to form what architects call architraves, like the beam over the top of a door. These were probably lifted up there on wooden platforms which were dismantled after construction. But these lintels were not simply lowered. Holes, tabs and joints were dug into the rocks so that the architects could insert tab A into slot B and fit them all together, like a very heavy piece of IKEA furniture. Sure, this is very advanced engineering for that time period, but unlike what many Internet forums say, it's not impossible. Builders may have lived a few thousand years before cranes and power tools, but they still had that good old human ingenuity... which we tend to overlook. Also, never underestimate the power of a good ramp and pulley system. Archaeologists believe that major work on Stonehenge continued until around 1500 BC, and that in that period more earthworks were dug and the bluestones were rearranged several times. But who built the structure and how are actually not the biggest questions scientists and historians have asked. Instead the real mystery is how the stones got there. You see, the great sarsen are made of sandstone, and the bluestones are variously made of rhyolite, dolerite, and other types of rock. But none of them match the geology of the nearby area. Luckily, no matter how far a stone has traveled, it still has the same geological age and composition as the formation it came from. So, after analyzing the mineral composition of Stonehenge's stones, as well as determining its age with other forms of radiometric dating, geologists were able to hunt for outcrops that match its characteristics. And we think we've found some answers. While there is still much debate, many scientists believe that the sarsens came from a region called the Marlborough Downs, about 32 kilometers from Stonehenge. And the blue stones most likely came from the Preseli Hills of Wales, more than 200 kilometers away. A 2015 study by the journal Antiquity even identifieda site that not only matches the bluestone geology, but also shows evidence of quarrying during the right time period. Researchers have suggested that this may actually be a site where Stonehenge rocks were quarried. Which is really surprising. Of course, this still doesn't explain how people moved the rocks. This seems like a tall order, so much so that it has been proposed that the rocks were not moved by humans at all. For once, though, I'm not talking about aliens. I'm talking about glaciers. It has been suggested several times that these enormous stones may have been drops of glacial stone, transported by advancing glaciers and deposited as the ice retreated. But modern archaeologists tend to disagree with this. First, they point out that there is a lack of reliable evidence of glacial activity on the Salisbury Plain. We see no large piles of rocks transported by glaciers, and certainly no deposits of the kind of stones used to build Stonehenge. Second, they argue that glaciers are not needed to explain the movement of these megaliths. Once again, human ingenuity is enough. For example, some researchers believe the rocks may have traveled over water. Ancient peoples could have loaded them onto boats and transported them along rivers and coasts. Some people have even traced specific waterways that could have carried the bluestones from the Preseli Hills in Wales to Stonehenge. On the other hand, the stones could also have moved on land. In 2016, a group of students at University College London conducted an experiment to test how difficult it would be to move a megalith. Inspired by the technologies of ancient Japan, they built a large wooden sled placed on a path of wooden logs. They loaded about a ton of stone onto the sled and dragged it across Gordon Square in London. With only ten people pulling, they managed to move the rock at up to three and a half kilometers per hour. So perhaps the architects of Stonehenge used a similar technique. Or, as other scientists have pointed out, perhaps they simply gathered a group of people and transported the rocks. All in all, it's hard to say which of these ideas – if any – is closer to the truth, because no one has found any direct evidence of a transportation route. After all, it's been an awfully long time. But there is good reason to suspect that people were at least capable of moving these megaliths without the help of magic or tractor beams. Historians are still investigating why they might have faced so much trouble, but either way, with all the hard work that went into building it, it's pretty clear that Stonehenge was important. It may have served several purposes, but scientists know for sure that it was a long-used burial site. The cremated remains of more than 60 people were removed from beneath the monument and it is estimated that over its centuries of use there may have been more than 150 burials at the site. For a long time we didn't know who these people were, but recent research has begun to unravel that mystery too. New excavations at Stonehenge in 2008 opened the door to more modern scientific analyzes of these remains, including a technique called stable isotope analysis. Unlike radiocarbon dating, this method looks at isotopes that have not decayed much over time. And instead of being used to determine age, it can be used to examine the chemical composition of remains. Much like the stones themselves, the Stonehenge bodies retain chemical traces of the environments they lived in, gleaned from the water they drank and the locally grown food they:.