That detail alone gives a sense of the scale involved. A ringfort, or rath, is a roughly circular earthwork enclosure, typically dating from the early medieval period and used as a farmstead or dwelling. Most were single-banked; this one at Rathard is bivallate, meaning it has two concentric banks with a fosse between them, making it a more elaborate construction than the majority of its kind.

The monument measures approximately 72 metres north to south and 71 metres east to west, with both banks surviving to considerable height despite centuries of neglect and some deliberate levelling. The inner bank is round-topped, about five metres wide at its base and rising roughly 1.7 metres above the intervening fosse, which is flat-bottomed and around two metres wide. The outer bank is broader and flatter, also five metres across its crest, and standing slightly over 1.7 metres above the fosse on its inner face. A narrow entrance, just 1.6 metres wide, opens to the west-southwest. The north-east section has suffered some damage, with part of the outer bank and possibly the inner bank levelled in that quadrant, and the interior is now dense with nettles and bramble. One further geographical oddity: the northern quadrant of the fort sits across a field boundary that serves simultaneously as both a parish and a townland boundary, meaning this single earthwork straddles two administrative divisions that have presumably been defined around it, or perhaps because of it, for generations.