It is easy to walk past without registering what you are looking at, which is, in itself, part of what makes such sites quietly remarkable. The ground still holds its shape after more than a thousand years.

By 1837, when the first edition of the Ordnance Survey six-inch map recorded this part of Longford, the site was already simply labelled 'Fort', the cartographers noting a subcircular enclosure but offering no further explanation. A report from 1976 describes the structure more precisely: a raised oval area measuring roughly 35 metres east to west and 34 metres north to south, enclosed by a low bank of earth and stone with an external fosse, the term for a defensive or boundary ditch dug around an enclosure. The whole thing is now defined primarily by a scarp, a slight but perceptible change in ground level where the old bank has slumped and settled over the centuries. Where the original entrance once stood is no longer distinguishable.