The site exists, as far as current knowledge goes, only as a ghost, a circular mark pressed into the crop above it, legible from the air but entirely absent at eye level.

The enclosure came to light through aerial photographs taken in 1965 and 1966, which revealed a circular cropmark. Cropmarks form when buried features, ditches, banks, or foundations, affect the growth of whatever is planted above them; crops over a filled ditch tend to grow taller and greener, while those over compacted ground may be stunted. The result, invisible from the field's edge, can be striking when seen from altitude. What the circular outline at Parkstown once enclosed, whether a ringfort, a prehistoric settlement, or some other structure, is not recorded. The reclamation of the land it sits on has buried the surface archaeology entirely, leaving the aerial photograph as the primary evidence that anything is there at all.