Aerial view of Castilly Henge with volunteers marking out the position of the newly discovered stone circle
New findings are part of a project to improve the condition of Castilly Henge near Bodmin. © Historic England/CAU
New findings are part of a project to improve the condition of Castilly Henge near Bodmin. © Historic England/CAU

Historic England Research Sheds New Light on Ancient Cornish Monument

New research by Historic England and the Cornwall Archaeology Unit (CAU) has revealed a previously unknown stone circle inside Castilly Henge near Bodmin.

The first modern archaeological surveys of Castilly Henge near Bodmin have been carried out as part of a project to conserve and better understand the site.

Castilly Henge is believed to have been built during the late Neolithic period (about 3000 to 2500 BC). Defined by an external bank and an internal ditch, it would have formed an amphitheatre-like setting for gatherings and ritual activities. Previous researchers have suggested that the site was used as a theatre (Playing Place or plen-an-guary) in the Middle Ages, and then as a battery during the English Civil War.

The opportunity to apply modern survey methods to this intriguing monument arose in 2021, when it was included in a Monument Management Scheme (MMS), a partnership between Historic England and the CAU to conserve and repair monuments on Historic England’s Heritage at Risk Register.

Volunteers coordinated by the CAU cleared the site of vegetation that threatened below-ground archaeological deposits. This work enabled teams from Historic England to carry out the first detailed topographic and geophysical surveys of Castilly Henge.

The surveys, which will be detailed in a Historic England report released later this year, revealed:

  • Traces of a long-buried stone circle in the centre of the henge, making this only the second henge with a stone circle in Cornwall.
  • Detailed information about the henge’s original form and its modification over time.

The research at Castilly Henge has given us a deeper understanding of the complexity of this site and its importance to Cornish history over thousands of years. It will help us make decisions about the way the monument is managed and presented so that it can be enjoyed by generations to come.

Ann Preston-Jones, Heritage at Risk Project Officer Historic England

The help of the local volunteers has been invaluable in removing the bracken and scrub obscuring the henge. Over the winter, thirteen people gave 111 hours of their time and now the monument is looking so much better. The project has also re-fenced the field and the farmer is happy to start grazing again, improving the long-term management of this amazing archaeological site.

Peter Dudley, Senior Archaeologist Cornwall Archaeological Unit

Castilly Henge is on Historic England’s Heritage at Risk Register because its location makes it difficult to look after, and as a result the earthworks and part of the interior were heavily overgrown with bracken.

As part of the MMS, volunteers have removed the bracken and other damaging vegetation from the monument, making it visible in the landscape again. The site has now been fenced, allowing it to be grazed.


Castilly Henge is protected as a scheduled monument. This late Neolithic henge monument is located at the centre of Cornwall, overlooking a major junction on the A30 trunk road with the A391 to St Austell and A389 to Bodmin. It has well-preserved earthworks and survives as an oval enclosure measuring 68 metres long by 62 metres wide, with a level interior measuring 48 metres long by 28 metres wide. The surrounding ditch is 7.6 metres wide and 1.8 metres deep, with an outer bank up to 1.6 metres high.