No earthwork interrupts the hillside, no obvious dip or rise announces itself underfoot. The monument exists, for practical purposes, only from the air.

The site first appeared on the Ordnance Survey's six-inch map of 1839, recorded as a large circular enclosure roughly forty metres in diameter. By 1990, aerial photography had revealed what that cartographic outline actually represented: a cropmark, the kind of faint signature that buried archaeology leaves in growing vegetation during dry summers, when soil above a fosse or bank drains differently from the surrounding ground and the difference shows up in the colour and height of crops or grass above. In this case the photographs showed a central raised area enclosed by a fosse, which is a defensive or boundary ditch, and an outer bank. Two further linear cropmarks, running roughly east to west, one to the north and one to the south of the enclosure, may be connected to the same complex, though their relationship to the circular feature is not fully understood.

What the enclosure was originally built for, and by whom, remains an open question. Circular enclosures of this general type in Ireland range from early medieval ringforts to prehistoric ceremonial monuments, and without excavation it is difficult to say more than that something significant enough to leave a forty-metre impression once occupied this hillside. The site is, in the strictest sense, invisible, and that invisibility is itself the most striking thing about it.