What survives today is only a portion of what was once a roughly circular earthwork some 38 metres in diameter, and even that partial survival is a matter of luck and geometry.

The first Ordnance Survey mapping of the area, carried out in 1840, shows the enclosure extending further northward than it does now, before a field boundary cutting across it from northwest to southwest effectively severed that section. By the time the site was mapped again in the 1953 to 1954 edition, the picture had contracted further. What remains is concentrated in the southern arc, where a flat-topped raised platform, standing about 1.2 metres high and measuring roughly 18 metres north to south by 9 metres east to west, is enclosed by a low bank. The bank, around 2 metres wide at its base, has in most places been worn down to little more than a scarp. A shallow outer fosse, the term for a ditch dug around an enclosure as part of its original boundary definition, traces the base of the platform on the surviving arc from south through west to northwest, though it is now barely 20 centimetres deep. Field boundaries cutting in from the north and east have removed the platform entirely on those sides.

Enclosures of this general type are found across Ireland and are often associated with early medieval settlement, sometimes functioning as the boundaries of a ringfort or a small defended farmstead. The precise date and function of the Aughnagomaun example remain unrecorded, but its position is telling. Set on the highest point of otherwise flat and poorly drained ground, with open views in every direction, it occupies the kind of slightly elevated, slightly drier spot that people repeatedly chose for habitation across many centuries. The modern fields have done their slow work on it, but the platform and its faint outer ditch are still legible in the grass for those who know what they are looking at.