The remains of a gigantic monument featuring at least 90 stones has been found buried a mile from Stonehenge.
The stones, which are thought to be 4,500-years-old, with some measuring nearly 15ft, are lying on their sides covered by three feet of earth.
They were discovered by archaeologists using ground-penetrating radar around the famous stone circle on Salisbury Plain.
It is believed the monoliths lined an impressive "arena" that may have been used for religious rites or solstice rituals.
Archaeologists have hailed the discovery beneath Durrington Walls super-henge - a circular enclosure ringed by a ditch and bank that at nearly a mile across is the largest earthwork of its kind in the UK - "truly remarkable".
Professor Vince Gaffney, from the University of Bradford, one of the archaeologists leading the project, said: "We're looking at one of the largest stone monuments in Europe and it has been under our noses for something like 4,000 years.
He added that it is is presumed to be "a ritual arena of some sort".
Prof Gaffney believes that the stones may have been planted by the same people who built Stonehenge, but is sceptical about a direct link between the two monuments.
Dr Nick Snashall, National Trust archaeologist for the Avebury and Stonehenge World Heritage Site, said: "These latest results have produced tantalising evidence of what lies beneath the ancient earthworks at Durrington Walls.
"The presence of what appear to be stones, surrounding the site of one of the largest Neolithic settlements in Europe adds a whole new chapter to the Stonehenge story."