Preseli spotted dolerite was mined in the Welsh Mountains 200 miles away
Archaeologists have discovered a mini-Stonehenge, a mile from the site of Wiltshire's famous stone circle.
"Bluehenge", named after the hue of the 27 stones from Wales which once formed it, has been described by researchers as a "very important" find.
All that now exists of the 5,000-year-old site is a series of holes where the dolerite monoliths once stood.
Bluehenge lies at the end of the "Avenue" - a pathway connecting the larger Stonehenge to the River Avon.
The remains of the monument were unearthed over the summer by researchers from Sheffield University.
It is thought it was erected around the same time as its neighbour Stonehenge.
The circle was made using the Preseli spotted dolerite stone.
It is a chemically altered igneous rock - harder than granite - which was mined in the Preseli Mountains in Pembrokeshire and dragged 200 miles to the site on the banks of the river.
Full details of the Bluehenge discovery will be published in February.