A small circular embanked enclosure, roughly fifteen to twenty metres in external diameter, sits on the floor of a gentle northeast-to-southwest valley or fold in the landscape. Walk across the pasture today and you would find no trace of it at all; it simply does not register at ground level.

The only record of its outline comes from the 1839 edition of the Ordnance Survey six-inch map, one of the most systematic and detailed cartographic exercises ever carried out in Ireland, during which surveyors documented features that have since been swallowed by agriculture or time. Embanked enclosures of this general type are found across Ireland and are thought to date from the early medieval period in many cases, though without excavation it is rarely possible to say with certainty what a particular example was used for. They may have served as farmsteads, animal enclosures, or ritual spaces. At fifteen to twenty metres across, this one would have been a modest affair, perhaps a single household's boundary rather than any larger settlement.

What makes Killowen quietly notable is how completely it has been absorbed. The valley setting may have contributed to its preservation beneath the soil while simultaneously making it invisible from above. It survives as a mark on an old map, a shape recorded by nineteenth-century surveyors who noticed something their successors on foot would not.