Stonehenge is one the UK’s most visited tourist attractions – and one of the world’s most enigmatic ancient monuments. People come from all over the world to stare at the iconic stone pillars and wonder how, and why, they were put in place.

The site may be instantly recognisable, but there is far more to it than first meets the eye. As archaeologists study this area, mystery after mystery unfolds. But a coherent story may be beginning to emerge.

That has been particularly true over the last decade. Researchers have been studying not just the monument itself, but the area around it, hoping to find clues in this intriguing landscape of prehistoric monuments.

Underground imaging and excavation have revealed that Stonehenge was once part of a complicated network of structures: ancient burial mounds, unknown settlements, processional routes and even gold-adorned burials. The finds paint a picture of a far more mysterious and elaborate Neolithic and Bronze Age world than previously thought.

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One such project that looked at Stonehenge in this holistic way was the Stonehenge Hidden Landscapes Project, which ran from 2010 to 2014. Underground radar and magnetic imaging techniques revealed that Stonehenge lies at the centre of a complex web of structures covering an estimated 4.5 square miles (12 sq km). The project caused a media frenzy in 2015, when scientists announced the finding of a potential ‘Superhenge’ at nearby Durrington Walls – a huge 500m (1,640ft) diameter stone circle.

However, this frenzy was short-lived. When excavating the site, the archaeologists didn’t find any stones. Instead, they found that timber posts once stood here. After they were removed, the holes were filled with chalk and then covered in earth to form a henge bank. On radar scans, the gaps in the loose chalk had looked like stones.

Despite this setback, UK lead for the Stonehenge Hidden Landscapes Project Vincent Gaffney stressed that the project revealed hundreds of new features and many sites never seen before. “Following this survey, we know not only where things are but where they aren’t as well,” said Gaffney, an archaeologist at the University of Bradford.

These kinds of surveys are key, Gaffney said, because they allow archaeologists “to investigate all areas of land equally, and not just the monuments we know. This allows us to interpret the evidence in a more sophisticated manner.

“What this has revealed is a completely unknown monumental phase of Durrington Walls. In between the Neolithic village and the massive earthwork was a massive ring of posts somewhere between 4-6m (13-20ft) in height – a minimum of 200 and perhaps as many as 300. This is completely new and would have been missed entirely without the survey.”

The finding of another huge monument in the area has changed the way archaeologists look at the development and history of the region. “Increasingly, I would suggest that we are beginning to see the mosaic of blank areas and monuments as suggesting processional movement,” said Gaffney.

In other words, the landscape was used in religious or ceremonial processions related to the monuments.

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Mike Parker Pearson of University College London’s Institute of Archaeology, who led the Stonehenge Riverside Project from 2003 to 2009, thinks that the posts at Durrington Walls were put up with the intention that they would be taken down soon after. “They may only have stood for a matter of months before they were replaced by the henge bank and ditch,” he said. “Their purpose seems to have been to mark the perimeter of the great village, by now abandoned. So perhaps the posts were a monument to the people who lived here while building Stonehenge.”

Whatever the monument was used for, it shows that Stonehenge isn’t alone in this landscape. Understanding the significance of Stonehenge depends on understanding everything else around it as well.

The Stonehenge Riverside Project found that Stonehenge was built in two phases. The first – a ditch, bank and circle of bluestones – was built 500 years earlier than previously thought, more than 4,500 years ago. The second phase, when the larger, iconic outer circle was erected, came about 500 years after the first.

The area, however, was occupied beginning around 9,000 years ago, suggesting it had significance long before Stonehenge was built.

Twenty miles (30km) away lies the less well-known but just as significant site of Avebury, home of the largest stone circle in Europe. But the Neolithic reach of this area extended even further – such as into Wales, where prehistoric Britons procured the bluestones for Stonehenge’s inner circle.

Meanwhile, Parker Pearson says, it seems that the big stones at Stonehenge came from the Avebury area.

This suggests that these significant Neolithic landscapes – Salisbury Plain, Avebury and the Preseli hills in Wales, another area rich with prehistoric monuments – were linked. And holding that link together was Stonehenge.

Parker Pearson suggests that the Welsh bluestones were the first to be put in place at Stonehenge, and that it was the monument that they came from that was important. The stones would have been considered to be ancestral symbols of western Britons, he said, and “bringing them to Salisbury Plain was an act of unification of the two main Neolithic peoples of southern Britain.”

Even today, the Preseli hills are dotted with dolmens (ancient tombs). “The density of dolmens reveals that this was an important region (both politically and spiritually) some 700 years before Stonehenge,” Parker Pearson said, making it “possibly a leading territory within western Britain in the centuries before 3000 BC.”

Question time

But even if we agree with the theory that bringing the stones from Wales was a symbolic and even political, act, it presents another mystery: how did prehistoric Britons move those huge stones?

Some suggest that people didn’t move the stones at all, and that instead, glaciers transported the stones across southern Britain. But the finding of two ancient stone quarries in Preseli ended that debate for the most part.

Scientists also have experimented with ideas of how to transport the large stones 160 miles (260km) from Wales. According to Parker Pearson, they discovered that moving small megaliths like the bluestones, which mostly weighed 2 tons or less, was not actually that difficult – even with just dragging the stone on a sledge.

In another recent finding, archaeologists discovered the cremated remains of people buried at Stonehenge. The Stonehenge Riverside Project’s 2008 excavation retrieved about 58 burials, including at least nine men – and 14 women. As it is thought that anyone buried at Stonehenge had elevated social status, this therefore poses questions about the role of women in the Neolithic period.

“It frequently seems that there is always something new from Stonehenge, but I continue to be surprised that we keep finding so much – even in areas that have been studied intensively for years,” said Gaffney. “The latest findings from Durrington demonstrate that new technology doesn’t just find new sites, it dramatically transforms how we understand known sites.

“It also emphasises not just how unique Stonehenge was, but how important the landscape around that monument was – and that we are still just beginning to understand how it developed and what it meant to the people who built Stonehenge.”

Even so, no matter how many new discoveries are made, it seems that Stonehenge will only continue to throw up new questions for scientists and the media to ponder. These Neolithic people had huge skill and ambition.

Such a huge monument erected so perfectly, over many centuries, is not something easy for us to understand in our fast-paced, modern world.

This story is a part of BBC Britain – a series focused on exploring this extraordinary island, one story at a time. See every BBC Britain story by heading to the Britain homepage; you can also follow us on Facebook and Twitter.