Walk across the pasture at Mullaghanee and the ground gives nothing away, no earthwork, no ridge, no scatter of stone. The enclosure is there nonetheless, betrayed only from the air, where a dry summer will cause the grass above buried banks and ditches to yellow at a different rate from the surrounding field, tracing the outline of a structure that was substantial enough, roughly fifty metres across, to be worth marking on two separate maps centuries after it had sunk entirely below the surface.

A rath, sometimes called a ringfort, was a circular enclosure typically built during the early medieval period, defined by an earthen bank and an outer fosse, or ditch, and used as a farmstead or place of habitation. The one at Mullaghanee sits towards the top of a drumlin, the smooth whale-backed ridge of glacially deposited material that gives this part of Monaghan its rolling, lumpen character. Its position on the north-east side of the drumlin's spine would have offered a measure of elevation and outlook. It appears on McCrea's map of County Monaghan, published in 1793, and again on the Ordnance Survey six-inch map of 1834, where it is marked in gothic lettering as a fort, the conventional cartographic signal for a monument of some antiquity. A second rath lies roughly a hundred and seventy metres to the west-north-west, which suggests the area was once a more populated or at least more organised landscape than the empty pasture implies today. By the time aerial survey work was carried out in 1995, the cropmark pattern was clear enough to define both the bank and the outer fosse, confirming what the old maps had been recording all along.