Set on a low but distinct rise in the Co. Westmeath grassland, this ringfort, or rath, has been so thoroughly worked over that its original form survives only in outline and inference. A rath is an early medieval farmstead enclosure, typically defined by one or more earthen banks and ditches, within which a family would have lived and kept livestock. Here, the enclosing bank has been levelled across much of its circuit, from the north-north-east around to the east-south-east, leaving only slight traces at the north and south-east. What remains is a sub-circular scarp in the ground, a kind of ghost of a perimeter rather than a standing earthwork.

The 1837 edition of the Ordnance Survey six-inch map still shows the site as a small circular enclosure, which means the damage is largely a post-Victorian story. Quarrying has been the principal culprit, gnawing into the fabric of the monument until much of it was gone. A later intrusion compounded the loss: at some point after the rath fell out of use, the southern half of the interior was reorganised into a small sub-rectangular enclosure, roughly 16.5 metres north to south by 18 metres east to west, bounded by an earth and stone bank. This kind of secondary reuse of older earthworks is not unusual in the Irish landscape, where convenient rises and pre-existing boundaries were often pressed into service for new purposes across the centuries. More intriguing is a depression at the centre of the interior, which may indicate a souterrain, an underground stone-lined passage or chamber associated with early medieval settlement, used variously for storage, refuge, or ventilation of a dwelling above. Whether anything survives below ground at Calliaghstown remains an open question.