That impenetrability is part of what makes it interesting. The enclosing bank, only thirty to forty centimetres high and two to three metres wide, traces an oval roughly forty-four metres across from east to west and thirty-four metres from north to south. At the north-east and eastern sides, the surrounding field drops away by as much as a metre and a half below the enclosure's rim, a subtle but distinct topographical wrinkle that suggests the site has quietly shaped the landscape around it for a very long time.

Ringforts, known in Irish as raths when they are earthen rather than stone-built, were the most common form of enclosed settlement in early medieval Ireland, typically serving as the farmsteads of farming families between roughly the fifth and twelfth centuries. They are defined in their simplest form by a circular or near-circular bank, often accompanied by a fosse, which is a ditch dug outside the bank to reinforce it. At Glenmore, however, no trace of a fosse survives, and the original entrance has been lost entirely, leaving the structure stripped back to its most elemental form. The site appears on the 1837 edition of the Ordnance Survey six-inch map, where it is marked as a circular enclosure with the label "Fort", indicating that even in the early nineteenth century it was recognisable and noted, if not fully understood by those doing the surveying.