For generations, it has been scrambled up with pride by students at Marlborough College. But the mysterious, pudding-shaped mound in the grounds of the Wiltshire public school now looks set to gain far wider acclaim as scientists have revealed it is a prehistoric monument of international importance.
After thorough excavations, the Marlborough mound is now thought to be around 4,400 years old, making it roughly contemporary with the nearby, and far more renowned, Silbury Hill.
The new evidence was described by one archeologist, an expert on ancient ritual sites in the area, as "an astonishing discovery". Both neolithic structures are likely to have been constructed over many generations.
The Marlborough mound had been thought to date back to Norman times. It was believed to be the base of a castle built 50 years after the Norman invasion and later landscaped as a 17th-century garden feature. But it has now been dated to around 2400BC from four samples of charcoal taken from the core of the 19 metre-high hill.
The samples prove it was built at a time when British tribes were combining labour on ritual monuments in the chalk downlands of Wiltshire, including Stonehenge and the huge ditches and stone circle of Avebury.
History students at the college will now have the chance to study an extraordinary example just a stone's throw from their classroom windows. Malborough's Master Nicholas Sampson said: "We are thrilled at this discovery, which confirms the long and dramatic history of this beautiful site and offers opportunity for tremendous educational enrichment."
The Marlborough mound has been called "Silbury's little sister", after the more famous artificial hill on the outskirts of Avebury, which is the largest manmade prehistoric hill in Europe.
Marlborough, at two-thirds the height of Silbury, now becomes the second largest prehistoric mound in Britain; it may yet be confirmed as the second largest in Europe.
Jim Leary, the English Heritage archeologist who led a recent excavation of Silbury, said: "This is an astonishing discovery. The Marlborough mound has been one of the biggest mysteries in the Wessex landscape. For centuries, people have wondered whether it is Silbury's little sister, and now we have an answer. This is a very exciting time for British prehistory."
The dating was carried out as part of major conservation work amid concerns that tree roots could be destabilising the structure.
Kennedy, Maev. 2011. "Marlborough mound mystery solved – after 4,400 years". Guardian. Posted: May 31, 2011. Available online: http://www.guardian.co.uk/science/2011/may/31/malborough-mound-wiltshire-silbury-neolithic