The enclosure at Drumgill is a multivallate fort, meaning it is defined not by a single bank and ditch but by a concentric series of them, each one amplifying the defensive logic of the last. Three earthen banks, separated by two substantial fosses (the ditches cut into the earth between the banks), ring a roughly oval interior measuring about 39 metres north to south and 35 metres east to west. The outer bank alone stands nearly four metres high at its north-western arc. The whole thing sits at the top of a hill, which was the point.

The site has the structural hallmarks of an Irish ringfort, or rath, a form of enclosed farmstead or settlement that was common across Ireland roughly between the early medieval period and the early medieval period's end, broadly the fifth to twelfth centuries. A single bank and ditch was the norm; three concentric rings like those at Drumgill indicate either higher social status or a more acute concern with defence, possibly both. The original entrance is still legible, positioned to the east-south-east, where narrow causeways of raised earth carry a visitor across both fosses rather than requiring a scramble down and up through them. Inside the innermost bank, to the north-west, there is a puzzling linear depression with an L-shaped spur off its southern end. It may be a souterrain, an underground stone-lined passage or chamber used for storage or refuge, though no stonework is visible at the surface. About 150 metres to the north-west lies a separate rath, suggesting this was once a more populated corner of the Meath landscape than it now appears.

The site slopes gently downward toward the east and sits against the south-western edge of a wood, which means its banks and fosses are best read from the southern and western approaches, where the external height of the earthworks is most pronounced. The innermost bank, modest enough from the inside at under a metre and a half, presents a face of over three metres to anyone approaching from outside, a reminder that these proportions were not accidental.