Stone monoliths found buried near Stonehenge could have been part of the largest Neolithic monument built in Britain, archaeologists believe.
The 4,500-year-old stones, some measuring 4.5m in length, were discovered under a metre of earth at Durrington Walls superhenge.
The monument was on “an extraordinary scale” and unique, researchers said.
The Stonehenge Hidden Landscapes team has been creating an underground map of the area in a five-year project.
Remote sensing and geophysical imaging technology has been used to reveal evidence of nearly 100 stones without the need for excavation.
The monument is just under three kilometres from Stonehenge, in Wiltshire, and is thought to have been a Neolithic ritual site.
Experts think it may have surrounded traces of springs and a dry valley leading into the River Avon.
Although no stones have been excavated they are believed to be fashioned from sarsen blocks found locally.
Sarsen stones are sandstone blocks found mainly on Salisbury Plain and the Marlborough Downs in Wiltshire.
A unique sarsen standing stone, The Cuckoo Stone, remains in the field next to Durrington Walls.
The stones are believed to have been deliberately toppled over the south-eastern edge of the bank of the circular enclosure before being incorporated into it.
