Our early Medieval theme runs from the Iron Age through the Early Christian period, or roughly 200BC through to 1000AD. This allows us to include non-Christian features like fogous and round houses, as well as stone crosses and holy wells.
Any attempt to categorise sites is fraught with problems. An ancient gathering place may have been later converted into a hill fort and perhaps thereafter into an Iron Age defensive structure: think Chun Castle with its neighbouring quoit. So allow us some latitude and enjoy searching.