Stonehenge Explained
More Than a Circle of Stones
Stonehenge on Salisbury Plain in Wiltshire is the most visited and most debated prehistoric monument in the world. Roughly five million people pass through its visitor centre each year, and hardly a decade goes by without a significant new research discovery prompting fresh headlines. Yet despite the attention, some of the most fundamental questions about Stonehenge — who exactly built each phase, what it was for, how some of the stones got there — remain genuinely contested among specialists.
What can be said with confidence is that Stonehenge was not built in a single act of construction but accumulated over roughly 1,500 years, from around 3000 to 1500 BC, through a series of distinct phases that reflect changing intentions and a changing society. The monument we see today is the product of multiple generations of builders, each working with and against the legacies of their predecessors.
Phase One: The Earthwork Enclosure
The earliest structure at Stonehenge, dated by radiocarbon to around 3000 BC, was not a stone monument at all. It was a circular enclosure — a henge — defined by a ditch and an inner bank roughly 110 metres in diameter, with two main entrances. Just inside the bank was a ring of 56 regularly spaced holes, now called Aubrey Holes after the 17th-century antiquary John Aubrey who first noticed them. Radiocarbon dating of cremated human bone from these holes has established that they held cremation deposits, making the earliest Stonehenge primarily a monument to the dead.
Aerial photography and geophysical survey have revealed that Stonehenge did not stand in isolation even in this first phase. The Stonehenge Landscape is extraordinarily rich: long barrows, round barrows, processional avenues and pit alignments cluster in the surrounding kilometres, indicating that this part of Salisbury Plain was already a significant ritual landscape before the stone monument began.
The Bluestones: A Journey Across Britain
The most debated aspect of Stonehenge is the origin of the smaller stones — the bluestones — that form two settings within the monument. Chemical analysis has established that the bluestones are not local to Salisbury Plain. The majority are spotted dolerite and rhyolite from the Preseli Hills in Pembrokeshire, southwest Wales, some 250 kilometres to the northwest. A distinct group of volcanic ash stones has been matched to a specific outcrop at Pont Saeson, also in Wales.
The bluestones were first erected at Stonehenge around 2500 BC. How they were transported is one of the most studied and most argued questions in British prehistory. Three main routes have been proposed: an overland route using sledges on timber rollers; a sea and river route around the Welsh coast and up the River Avon to within a few kilometres of the site; and, more recently, the glacial hypothesis — that the stones were carried to within reach of Stonehenge by glacial action during an earlier ice age, requiring only final transport by human effort.
Most geomorphologists and archaeologists consider the glacial hypothesis insufficient to explain all the evidence, and favour human transport. A 2019–2020 excavation at the Preseli Hills site of Waun Mawn, where a dismantled stone circle was found partly matching Stonehenge's dimensions, proposed that an entire monument was taken apart and reconstructed at its present location — transforming the story from simple quarrying and transport to the relocation of an existing sacred structure.
The Sarsens: Engineering on a Grand Scale
The iconic silhouette of Stonehenge — the lintelled trilithons of the inner horseshoe and the outer circle of uprights connected by a continuous ring of lintels — was created in a single major building phase around 2500–2300 BC. These are the sarsen stones: large blocks of silcrete sandstone quarried from Marlborough Downs near Avebury, roughly 25 kilometres to the north.
The sarsen stones are enormous by any standard. The largest upright, the Great Trilithon's standing stone, weighs around 25 tonnes; the lintels of the outer circle average around 7 tonnes. Moving them from Marlborough Downs involved a journey of at least 25 kilometres across rolling downland, and erecting them required temporary ramps, levers, ropes and a workforce of significant scale. Experimental archaeology using full-scale replicas has shown that the basic techniques — timber sledges, rope hauls, A-frame levers — are feasible with large groups of workers, but the logistics of feeding and organising such a workforce remain remarkable.
The sarsen joinery is equally striking. The uprights of the outer circle have mortise-and-tenon joints cut into their tops, matching protruding tenons on the lintels. The lintels are also shaped with a slight curve to follow the circle's circumference, and they are connected to each other by tongue-and-groove joints at their ends. This is carpentry technique translated into stone, and it implies that the builders were working in a tradition of monumental timber architecture that preceded the stone monument — a hypothesis supported by evidence of large post-built structures elsewhere in the Stonehenge landscape.
The Aubrey Holes and Astronomical Alignments
The axis of Stonehenge is aligned with the midsummer sunrise and the midwinter sunset. At the summer solstice, the rising sun aligns with the Heel Stone — a large unworked sarsen standing outside the northeast entrance — and shines down the processional avenue toward the monument's centre. At the winter solstice, the setting sun aligns with the southwest, shining directly through the Great Trilithon.
This solar alignment has been known since the 18th century and is so precisely realised that it cannot be accidental. Whether Stonehenge was primarily an astronomical instrument, a temple oriented by astronomical principles, or a monument for whom solar alignment was one element among many, remains debated. Archaeoastronomers have proposed additional alignments — with the major and minor lunar standstills, with stellar rising points — though these claims vary considerably in the strength of supporting evidence.
A long-standing hypothesis proposed by Gerald Hawkins in the 1960s, that Stonehenge could be used to predict lunar eclipses by tracking the 18.6-year cycle of the moon through the Aubrey Holes, attracted enormous popular attention and considerable scholarly scepticism. The hypothesis required Stonehenge to function as a computing device, with stones moved around the circle as markers. It remains an interesting speculation rather than an established fact.
Who Built Stonehenge?
The earliest phase — the earthwork enclosure around 3000 BC — was built by Neolithic farming communities who had been living in Britain for roughly a thousand years, the descendants of the first agricultural settlers who had arrived from continental Europe around 4000 BC. These communities built the long barrow tombs that precede Stonehenge in the landscape.
The sarsen phase around 2500 BC coincides with the arrival in Britain of the Beaker culture, characterised by a distinct pottery style and associated with a major genetic influx from the continent, ultimately connected to steppe populations from the Pontic-Caspian region. Ancient DNA studies published since 2018 suggest that the Beaker migration largely replaced the earlier Neolithic population of Britain within a few centuries. The people who erected the sarsens were, in genetic terms, quite different from those who built the original earthwork.
This does not mean the Beaker people founded Stonehenge from scratch — the site was already ancient when they arrived — but it does complicate simple narratives about a single building people.
Visiting Stonehenge Today
Stonehenge is in the care of English Heritage and sits within a UNESCO World Heritage Site that also encompasses the nearby Avebury complex, the Silbury Hill mound and numerous associated monuments. The standard visitor experience involves a path around the outside of the monument at a respectful distance; access to the stones themselves is restricted to special pre-booked visits outside normal opening hours. The nearby visitor centre, opened in 2013, displays excavated objects and a reconstructed Neolithic settlement.
Open the map to explore Stonehenge in its wider landscape, alongside the barrows, avenues and enclosures that make up one of the world's great prehistoric sacred territories.