Archaeologists have discovered the remains of a massive stone monument buried under a thick, grassy bank only 3 kilometres from Stonehenge (Wiltshire, England). The hidden arrangement of up to 90 huge standing stones formed part of a C-shaped Neolithic arena that bordered a dry valley facing directly towards the river Avon.
     Researchers used ground-penetrating radar to image about 30 intact stones measuring up to 4.5 metres tall. The fragments of 60 more buried stones, or the massive foundation pits in which they stood, reveal the full extent of the monument.
     "What we are starting to see is the largest surviving stone monument, preserved underneath a bank, that has ever been discovered in Britain and possibly in Europe," said Vince Gaffney, an archaeologist at Bradford University who leads the Stonehenge Hidden Landscape project.
     The stones are thought to have been hauled into position more than 4,500 years ago to form the southern edge of a ritual arena centred on a natural depression. The stones appear to have joined up with a chalk ridge that had been cut into, to accentuate the natural border.
     Gaffney believes the stones were pushed over when the site was redeveloped by Neolithic builders. The recumbent stones became lost beneath a huge bank and were incorporated as a somewhat clumsy linear southern border to the otherwise circular "super-henge" known as Durrington Walls.
     1600 metres in circumference, Durrington Walls is one of the largest known henge monuments. It is surrounded by a ditch, and a 40 metre wide, 1 metre tall outer bank, built about a century after the Stonehenge sarsen circle. Archaeologists believe the newly discovered stone row could have been put in place at the same time or even earlier.
     The rise and fall of the newly discovered monument at Durrington Walls suggests that buildings were modified and recycled since the first stones were laid around 3100 BCE.
     Paul Garwood, an archaeologist and lead historian on the project at the University of Birmingham, said the the new discoveries at Durrington Walls changed fundamentally how researchers understood Stonehenge and the world around it. "Everything written previously about the Stonehenge landscape and the ancient monuments within it will need to be rewritten," he said.

Edited from BBC News, The Guardian (7 September 2015)