This is a rath, the commonest type of early medieval Irish enclosure, typically formed by an earthen bank and an outer ditch, known as a fosse, thrown up around a farmstead or settlement sometime between roughly the fifth and twelfth centuries. What makes this particular example worth pausing over is less its condition than its position: the hillock offers clear sightlines from the north-west around through north and east to the south-south-east, the kind of prospect that would have made it attractive to whoever chose to build here in the first place.

The enclosure is sub-circular in plan, measuring approximately 41 metres north to south and 34.5 metres east to west. The earthen bank that defines it is poorly preserved, and the fosse outside it is now only slight, but the interior is far from featureless: the ground within is uneven, scattered with depressions and low banks that hint at structures or activity that has long since collapsed back into the soil. Aerial photography taken in November 2011 suggested the presence of an outer bank as well, which would make this a multivallate ringfort, meaning one defended or defined by more than a single enclosing ring, a feature sometimes associated with higher-status settlements in the early medieval period. Around 390 metres to the north lies Archerstown church and graveyard, a pairing of early Christian monument types that is common across the Irish midlands and may reflect a broader pattern of settlement in this part of Westmeath.