A MAJOR project to reveal the secrets of a unique prehistoric ritual site described by experts as “Cornwall’s ancient sacred heart” has been given the green light thanks to a £42,990 grant from The National Lottery Heritage Fund, using money raised by National Lottery players.

Located just off the A30 near Bodmin, Castilly Henge is believed to have been built during the late Neolithic period (about 3000 to 2500 BCE). It is a substantial oval earthwork with an external bank and internal ditch, which would have formed an amphitheatre-like setting for gatherings and ritual activities. Its significance continued into the Early Bronze Age (c.2400-1500 BCE) when several high-status burial mounds or barrows were built close by.

Previous researchers have suggested that the site might have been used as a medieval open-air theatre known as a plen-an-gwari and then as a battery during the English Civil War.

The project is a collaboration between the Cornwall Archaeological Society, the Cornwall Heritage Trust and Historic England. It will involve a four-week archaeological excavation in September and October 2025 to target important questions about the monument’s character, date and potential later reuse.

The dig is informed by earthwork and geophysical surveys undertaken by Historic England’s Archaeological Investigation Team as part of a previous project in 2022. This found traces of a now-removed possible stone circle in the middle of the henge. Not all henges contain stone circles, and there is only one other known to survive in Cornwall.

There will be opportunities for a significant number of volunteers to be directly involved in the dig and work alongside seasoned excavators, as well as a wide range of outreach activities, tours and educational workshops to involve local communities in the project as much as possible. The works will be rounded off with a celebration and public open day. Historic England is also making a contribution towards the community outreach element of the project through a £10,000 grant.

The henge is currently at risk due to the threat posed by invasive vegetation. Modern development of the nearby road infrastructure and local service network, which lie within metres of the site, also pose potential risks.

Cathy Woolcock, chief executive officer at Cornwall Heritage Trust, said: “This is such an exciting opportunity for the local community to be directly involved in discovering more about one of Cornwall’s most important ancient sites and we’re so honoured to be involved.

“The henge has been at risk for some time – a threat which urgently needs to be addressed before this special place and the secrets it holds are potentially lost. This project is an exciting step forward in making that possible, firstly by uncovering Castilly’s story and then creating management plans to improve the biodiversity of the field and the condition of the monument so that it can be protected and sustainably managed for many years to come. We’re delighted that the National Lottery Heritage Fund sees the impact that this project will have and are hugely grateful to National Lottery players for making this funding possible!”