A new digital reconstruction of the monument discovered by the Stonehenge Riverside Project in 2009 suggests that the ring of stone sockets found at the southern end of The Avenue may well have been oval in shape, like the bluestone oval at the centre of Stonehenge. The stones had been removed thousands of years ago, but the sizes of the holes in which they stood indicate that this was a circle of bluestones, brought from the Preseli mountains of Wales, 240 km away.
     Excavations in 2009 by the Stonehenge Riverside Project uncovered nine stone holes, part of a ring of probably 25 standing stones. The monument was 10 metres across and surrounded by a henge - a ditch with an external bank. These standing stones marked the end of the Avenue that leads from the River Avon to Stonehenge, a 2800 metre processional route constructed at the end of the Neolithic period.
     The outer henge around the stones was built around 2400 BCE, but arrowheads found in the stone circle indicate that the stones were erected as much as 500 years earlier. When the stones were removed by Neolithic people, it is possible they were incorporated within Stonehenge during its major rebuilding around 2500 BCE. After this date, Stonehenge consisted of about 80 Welsh bluestones and 83 local Sarsen stones.

Edited from Mike Pitts, Past Horizons (14 September 2011)