Up to 90 standing stones, some originally measuring 4.5 metres long and dating back some 4,500 years, were discovered under an earthen embankment. The find was made at Durrington Walls, a so-called "Superhenge" located less than three kilometres from Stonehenge - thanks to hi-tech sensors. The site may have originally been used for rituals or as some kind of arena.

The Stonehenge Hidden Landscapes Project, a collaborative effort between the University of Birmingham and the Vienna-based Ludwig Boltzmann Institute for Archaeological Prospection and Virtual Archaeology (LBI ArchPro), found the site. "Durrington Walls is an immense monument and up until this point we thought it was merely a large bank and ditched enclosure, but underneath that massive monument is another monument," said Vincent Gaffney of the University of Bradford.

The newly discovered stones, which have yet to be excavated, are thought to have been toppled over, with the later Durrington Walls henge built over them. The monument, which lies in the Stonehenge World Heritage Site, is one of the largest known henges - a circle of stone or wooden uprights - ever found. It measures 500 meters across and more than 1.5 km in circumference. Surrounded by a 17.6 meter wide ditch and an embankment around 1 meter high, the site has long mystified archaeologists as one side is straight and the other curved.

Nick Snashall, a National Trust archaeologist for the Stonehenge site, said the findings provided "tantalizing evidence" of what lies beneath 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." Snashall said.

at/ks (afpe)