This is a rath, the most common form of early medieval enclosure in Ireland, typically used as a defended farmstead between roughly the sixth and twelfth centuries. What sets this particular example apart is the suggestion, lurking just beneath the surface, that something more may lie underground.

The rath at Comraghs measures approximately 28 metres east to west and just over 23 metres on its north-west to south-east axis, giving it a slightly oval, subcircular plan. Its earthen bank, between 3.8 and 5.8 metres wide at the base, survives to an external height of over a metre in places, and a complete outer fosse, or defensive ditch, rings the entire enclosure. The original entrance, just over a metre wide at its base, faces south; a gap on the northern side is now blocked by a tree. The rath was already old enough to be considered a fixed landmark when James McCrea included it on his map of County Monaghan in 1793, and at some point its bank was incorporated into a field boundary, with stone facing added along the north-north-west to north-east arc. Inside the bank on the north-west side, there is a grass-covered linear depression roughly 5.5 metres long and about 0.7 metres deep, and a second hollow of around 4 metres lies just outside the enclosure to the south-west. These depressions are thought to represent two collapsed sections of a souterrain, an underground stone-lined passage or chamber built into or beside raths, typically used for storage or as a place of refuge. If that identification is correct, the ridge at Comraghs holds rather more than it appears to from above.