What makes it particularly curious is not what you can see on the ground, but what you cannot: the feature appears on neither the 1840 Ordnance Survey Ireland six-inch map nor the 1897 twenty-five-inch edition, meaning it escaped the attention of the surveyors who documented almost every earthwork, field system, and hollow in this otherwise well-recorded landscape. Its existence only came to light through aerial and satellite imagery, the kind of slow, patient looking that occasionally turns up something the historical record missed entirely.

The enclosure, recorded under the reference LI032-183----, was compiled by archaeologist Caimin O'Brien on the basis of details provided by Edmond O'Donovan, and uploaded to the national record in November 2020. An enclosure of this type, a roughly circular earthwork that may once have defined a domestic, agricultural, or ceremonial space, is a common enough form in Irish archaeology, but their individual histories vary enormously. What gives this one a particular quality is its position. Lough Gur, visible just 410 metres to the south, is one of the most archaeologically significant lake landscapes in Ireland, associated with Neolithic, Bronze Age, and later activity across several millennia. Whether this enclosure belongs to any of those periods, or to a quite different era, is not yet established. A second enclosure lies 85 metres to the southwest, suggesting the hill may have supported more activity than the silent pasture currently implies. A relic field boundary running northwest to southeast cuts directly across the enclosure's outline, a detail visible in satellite imagery from 2017 and faintly discernible in earlier orthophotos from 2005 to 2013, suggesting the enclosure predates that field system, though by how much remains unknown.

The hill sits within the Lough Gur area, which is well signposted from the village of Bruff and from the R512 road between Limerick city and Kilmallock. The lakeshore itself has an interpretive centre and is freely walkable, but Knockfennell Hill is agricultural land, and access to the enclosure itself would require the landowner's permission. The feature is not marked on any public trail or signage. Those interested in identifying it should consult the Google Earth orthoimage associated with the record, since the outline is faint and easily missed without knowing where to look, particularly in summer when grass growth can obscure low earthworks entirely. Early spring or a dry late autumn, when vegetation is thinner and shadows are longer, offer the best chance of making out the circular form from a distance.