This year, a groundbreaking revelation has been unveiled concerning Stonehenge, one of the world's most enigmatic structures. A group of scientists presented compelling evidence in August that the Altar Stone, a prominent standing stone at the core of Stonehenge, was transported from northeastern Scotland, a distance of hundreds of miles, to its current location in southern England nearly 5,000 years ago.

In September, a subsequent study led by the same team of experts dismissed the theory that the stone originated from Orkney, an archipelago off the northeastern coast of Scotland, which is known for its Neolithic sites. The quest for the true origin of the monolith is ongoing. Now, a new study, published in Archaeology International, posits that Stonehenge may have been reconstructed in England between 2620 and 2480 BC to foster unity among ancient Britons amidst the arrival of new settlers from the European continent. This research also delves into the methods Neolithic people might have employed to move the 13,227-pound (6-metric-ton) Altar Stone over a distance of 435 miles (700 kilometers) from its place of origin.

The study, which builds upon the previous two, suggests a stronger connection between ancient societies in Scotland and England than previously believed, evidenced by the similarities between stone circles in these regions and Stonehenge in Wiltshire, on the southern edge of England's Salisbury Plain. These discoveries are illuminating the purpose of Stonehenge and the arrangement of its standing stones, a puzzle that has persisted since the 17th-century excavations began.

"These new insights have significantly broadened our comprehension of the original intent behind Stonehenge," said Mike Parker Pearson, lead study author and professor of British later prehistory at University College London's Institute of Archaeology. "It indicates that this site on Salisbury Plain held significance not only for the local inhabitants but also for people across Britain, so much so that they transported massive stones across vast distances to this single location."

The construction of Stonehenge is believed to have commenced as early as 3000 BC, unfolding over several phases in an area that has been inhabited for 5,000 to 6,000 years, according to researchers. Analysis has shown that bluestones, a type of fine-grained sandstone, and larger silicified sandstone blocks known as sarsens were utilized in the monument's construction.

The bluestones, thought to be the first stones placed at the site, were sourced from the Preseli Hills in west Wales, 140 miles (225 kilometers) away. The sarsens, used later, were obtained from the West Woods near Marlborough, approximately 15 miles (25 kilometers) away. It is theorized that the Altar Stone was positioned within the central horseshoe during a rebuilding phase, which the study authors estimate occurred between 2500 and 2020 BC.

During this rebuilding phase, the architects of Stonehenge are believed to have raised the large sarsen stones to form an outer circle and an inner horseshoe composed of trilithons, pairs of upright stones connected by horizontal stone beams, which continue to be a part of the monument today. The Altar Stone is the largest of the bluestones used in the construction of Stonehenge. Today, it lies recumbent at the base of the largest trilithon, barely visible through the grass.

While many questions persist regarding the exact purpose of Stonehenge and the Altar Stone, the monument aligns with the sun during the winter and summer solstices. "There is substantial evidence to suggest that these large stone monoliths hold ancestral significance, representing and perhaps even embodying the ancestors of those who placed them," Parker Pearson said. "The Altar Stone's position within Stonehenge is significant, as if you stand at the center of the stone circle, the midwinter solstice sun sets directly over its center."

During the winter, Neolithic people would gather near Stonehenge at the village of Durrington Walls, bringing pigs and cattle for a feast, as stated by Parker Pearson. Stonehenge was also the largest burial ground of its time, supporting the notion that the site may have served as a religious temple, a solar calendar, and an ancient observatory. Almost half of the Neolithic people buried near Stonehenge originated from outside Salisbury Plain. The new research introduces a political dimension to the narrative of Stonehenge's reconstruction. "The fact that all of its stones came from distant regions, setting it apart from over 900 stone circles in Britain, suggests that the stone circle may have had political as well as religious significance—as a monument of unity for the peoples of Britain, celebrating their perpetual bonds with their ancestors and the cosmos," Parker Pearson said.

The act of unity—transporting colossal stones over long distances—would not have been a simple task for Neolithic people. The study authors do not believe that boats at the time were capable of carrying the Altar Stone across coastal waters. "Although the wheel had been invented elsewhere, it had not yet reached Britain, so the massive stone blocks would likely have had to be dragged by wooden sledges gliding on wooden rails that could be continuously lifted and re-laid," Parker Pearson said.

The wooden sledge could have been equipped with shock absorbers made from vegetation to cushion the stone, which was prone to cracking during the lengthy journey, according to the study authors. Hundreds, and possibly thousands, of people would have been required to move the stone over land, and the journey could have taken around eight months, as noted by the researchers in the paper. "Travel by land would have provided far better opportunities for spectacle, pageantry, feasting, and celebration that would have attracted thousands of people to witness and participate in this extraordinary endeavor," the study stated.

The transportation of the massive stone from Scotland to southern England implies a network between two distant groups, fostered by collaboration and cooperation—something the researchers believe existed due to the striking cultural similarities in both locations. "They would have required significant coordination across Britain—people were literally pulling together—in a time before telephones and email to organize such an effort," Parker Pearson said. The Altar Stone is similar in both size and placement to other large horizontal blocks in stone circles found in northeast Scotland, according to the study authors. These recumbent stone circles have only been found in that part of Scotland, rather than the rest of England, suggesting that the Altar Stone may have been a gift from the northern Scottish community to signify a form of alliance. "Moreover, if you examine the layouts of some of the houses at Durrington Walls near Stonehenge, there is a striking similarity in their architecture to those found far north in the Orkney Islands, but rarely anywhere in between," Parker Pearson said. "We have also known for some time that people shared a style of pottery—called Grooved Ware—across the entire island of Britain. It appears to have been one of several innovations that originated in Scotland and spread south from 3000 BC onwards."

As an island, Britain's population has undergone multiple changes. The region's early farmers descended from people from the Middle East who arrived on the island about 6,000 years ago, introducing agricultural practices. The newcomers replaced the hunter-gatherer communities that had previously inhabited Britain and formed the majority of the population from 4000 to 2500 BC, according to Parker Pearson. However, around 2500 BC, people began to arrive in Britain from Europe, primarily from what is now known as Germany and the Netherlands, and it is around this time that Stonehenge was rebuilt, according to the study.

The researchers believe that the rebuilding process was "a response to a legitimation crisis brought on by this influx of new people" and an attempt to unite the Neolithic farmer population. The European arrivals, known as the Beaker people for the distinctive pottery they buried with their dead, brought technology such as the wheel and metalworking with them. "Within 16 generations over 400 years, it seems that most people had ancestries that were a mix of the two, yet this was a mix of 90% newcomer to 10% indigenous farmer," Parker Pearson said. "The genetic makeup of Britain's population almost completely changed over half a millennium."

Ultimately, the descendants of the Beaker people replaced the Neolithic farmers and became Britain's dominant population. Thus, Stonehenge, which brought "together these extraordinary and alien rocks which (symbolized) and embodied far and distant communities within a complex material and monumental expression of unity between people, land, ancestors, and the heavens," failed to unite the same communities that constructed it, the study authors noted. "The findings of this study shed most unexpected and highly impressive new light on the history of Stonehenge—a remarkable achievement considering how well-studied this famous site has been," said Duncan Garrow, a professor in the department of archaeology at the University of Reading specializing in European prehistory. Garrow was not involved in the new study.

Currently, researchers are intensifying their efforts to pinpoint the exact location in northeastern Scotland where the Altar Stone originated, said Richard Bevins, coauthor of the new study, as well as the previous studies this year concerning the Altar Stone. Bevins is an honorary professor in the department of geography and Earth sciences at the UK's Aberystwyth University. "It's really gratifying that our geological investigations can contribute to the archaeological research and the unfolding story as our knowledge has been improving so dramatically in just the last few years," Bevins said. "Our research is like forensic science. We are a small team of (Earth) scientists, each bringing their own area of expertise; it is this combination of skills that has allowed us to identify the sources of the bluestones, and now the Altar Stone."