The graves in the grounds Abbey of Cwmhir are a bit smaller than modern ones. That’s what the chief archaeologist of the Clwyd Powys Archaeological Trust, Nigel Jones, found out when he lay down in one to test out the size.

“No we are not going to re-use graves in the name of recycling,” a spokesperson said. “But we are going to try to investigate some of the many mysteries that haunt the history of the ruins of the Abbey of Cwmhir.”

To show the public some of the work the Abbey Cwmhir Heritage Trust has already been doing, and to possibly get people involved in future investigations, a drop-in open day is being held on Saturday, November 23.

A spokesperson said: “This is a chance to find out what has already happened and what we hope to achieve in the future. In the long term this could involve you.

“You may even be asked to lie in a grave but more likely investigate a trench with trowel and brush or assist with some advanced technology – what about high definition ground penetrating radar or prove your technique at making tea?”

In February of this year The Abbey Cwmhir Heritage Trust commissioned a drone photogrammetry survey by Julian Ravest of the Radnorshire Society which not only revealed the clear boundary of the precinct – the abbey’s closest grounds – signs of medieval ridge and furrow ploughing but also possible foundations of a structure at the east end.

This is very significant as one of the great mysteries of Cwmhir Abbey is why doesn’t it have an east end where the main business of the abbey took place, in the choir, singing psalms and praying eight times a day and in the presbytery, celebrating mass? Normally this part of an abbey was built first but at Cwmhir the huge nave was built and the east end, possibly, never.

A Trust spokesperson said: “You may have been to Hereford Cathedral which seems vast when you enter the nave, it has eight bays or arches down the side. Cwmhir had 14. It was the longest Cistercian nave in Europe and within inches of Winchester, the longest in the UK, and longer than Westminster Abbey.

“You might imagine Royal Wedding processing down its vast length. In fact it has been suggested that Llywelyn the Great, the most powerful man in Wales at the time, had Cwmhir built as a national cathedral for the investiture of his son Dafyd as his successor. In the end he was crowned at Strata Florida in 1238.”

The open day will take place between 11am and 3pm at the Philips Hall, at Abbeycwmhir (LD1 6PH). There will be tea, coffee and cakes available and the event aims to appeal to all ages.

There is plenty of parking outside or at Home Farm, by the Abbey. Tours of the abbey will be available at 12 and 2pm.