A site at Marden, near Devizes, rivalled Stonehenge and Avebury in its day, says English Heritage.

The group is about to undertake a six-week dig at the site close to the village, starting on June 28.

Unlike Stonehenge and Avebury, Marden Henge no longer has any surviving standing stones, but its sheer size is astounding.

Comprising a substantial and well-preserved bank with an internal ditch enclosing an area of some 10.5 hectares – equivalent to ten football pitches – it is one of the largest Neolithic henges in Britain.

Archaeologists are particularly intrigued by evidence of a huge mound at the centre of the henge similar to a smaller version of Silbury Hill.

The mound collapsed in 1806 and was levelled by 1817. English Heritage hopes to find out more about this feature by obtaining dating material from any surviving features within its centre.

Jim Leary, the English Heritage archaeologist who was involved in the recent restoration of Silbury Hill, said: “Marden Henge deserves to be understood more, partly because of its size, but also due to its proximity to the more famous stone circles at Avebury and Stonehenge.

“How Marden relates to them is another layer of interest which we want to study.

“We are potentially looking at a much more intricate system of Neolithic ritual sites in this part of the world than we previously thought.”

The Henge is on the road out of the village towards Beechingstoke, at Hatfield Farm, and is a popular picnic area.

Parish council chairman Peter Bell was pleased with the news. He said: “I hadn’t heard English Heritage were planning this, but I am delighted. It is an important local archaeological site and we don’t know nearly enough about it.”

The Henge is on the road out of the village towards Beechingstoke, at Hatfield Farm, and is on private land.

Sue Shepherd-Cross, who lives at Hatfield Farm, was delighted at the news. She said: “It is a remarkable place and it would be fascinating to find out more about it.”

The website Megalithic.co.uk describes Marden Henge, or Hatfield Earthworks, as the largest henge in Britain. It adds: “There is not much to see but bank and ditch. Plenty of atmosphere, though.”

* A midsummer’s eve picnic party is taking place at Marden Henge on Saturday June 26 at 8.15pm in aid of the Fairyland Trust which is a children’s conservation society.