A prehistoric burial site in Dorset has been revealed as Britain's oldest known circular enclosure, predating previous estimates by two centuries.
The Flagstones monument, near Dorchester, has been redated to approximately 3200 BC following advanced radiocarbon analysis of human remains, red deer antlers, and charcoal found at the site.
The new timeline, established by researchers at the University of Exeter and Historic England, positions Flagstones as a potential precursor to iconic later monuments such as Stonehenge.
The site's unique structure – it is a perfectly circular ditched enclosure containing both burials and cremations – presents a blend of characteristics from different eras.
“In some respects it looks like monuments that come earlier, which we call causewayed enclosures, and in others it looks a bit like things that come later that we call henges,” Dr Susan Greaney, from the University of Exeter, said.
“But we didn’t know where it sat between these types of monuments and the revised chronology places it in an earlier period than we expected.”
Flagstones was discovered in the 1980s during construction of the Dorchester by-pass. Excavations showed it was formed of a 100m diameter circular ditch made of intersecting pits, probably an earthwork bank.
Today half of the site lies beneath the by-pass, with the remainder beneath Max Gate, Thomas Hardy’s former home, now bequeathed to the National Trust.
Flagstones is a scheduled monument, with finds and excavation archives preserved at Dorset Museum.
At least four burials were found to have been placed in the enclosure pits – a cremated adult and three children who had not been cremated – and there were three partial cremations of adults elsewhere.
The similarity of the site to the first phase of Stonehenge, which has been dated to about 2900 BC, led to the assumption that Flagstones must be of a similar date.
The new findings suggest the early Neolithic activity, including the digging of pits, took place in about 3650 BC.
After a gap of many centuries, the circular ditched enclosure was created in about 3200 BC, with burials placed within it immediately afterwards.
A later burial of a young adult male under a large sarsen stone at the centre of the enclosure took place about 1,000 years or so after its initial use.
“The chronology of Flagstones is essential for understanding the changing sequence of ceremonial and funeral monuments in Britain,” Dr Greaney said.
“The ‘sister’ monument to Flagstones is Stonehenge, whose first phase is almost identical, but it dates to around 2900 BC.
“Could Stonehenge have been a copy of Flagstones? Or do these findings suggest our current dating of Stonehenge might need revision?”
Flagstones also shows connections to other significant sites, including at Llandegai in Gwynedd.
The study, ‘Beginning of the circle? Revised chronologies for Flagstones and Alington Avenue, Dorchester, Dorset’, is published in the journal Antiquity.