A rath is a ringfort, the most common type of early medieval settlement in Ireland, typically consisting of a raised earthen bank enclosing a circular area where a farmstead once stood. At Ballymackesy, that enclosure originally measured around fifty metres in diameter, large enough to have sheltered a household of some standing, yet the centuries and the gradual reorganisation of agricultural land have left it only partially intact.

The site was recorded on the Ordnance Survey six-inch map of 1841, which gives a useful baseline for understanding what has since been lost. By the time Denis Power compiled the monument record, the eastern and southern portions of the enclosing bank had already been cut back by field boundaries, leaving a truncated arc rather than a complete circuit. What does survive runs from the south-west through to the north-east, an earthen bank rising roughly half a metre on the interior face and slightly less on the exterior, with a scarped, or deliberately cut, edge defining the south-south-east to south-west section. The original entrance is still legible, a gap of about two and a half metres through the bank at the northern side, wide enough for a person or animal to pass through comfortably and consistent with how such entrances were typically positioned in Irish ringforts.

The interior is level, dry, and clear of overgrowth, which makes it easier than many comparable sites to read the surviving earthworks. The southern edge of the site is now defined by a field drain rather than the original bank, so the full extent of the enclosure in that direction has effectively been absorbed into working farmland. The surviving bank is modest in height and easy to miss if you are not specifically looking for it, but standing inside and looking north towards the entrance gap, the logic of the original structure becomes reasonably clear. The site sits in level pasture, so there is no dramatic topographical setting to help orientate the eye; the earthworks themselves have to do all the work.