' That phrase, common in antiquarian writing of the period, was a catch-all for any earthwork or enclosure whose origins seemed ancient and unexplained. The Danes in question were rarely, if ever, actually Viking; the term was applied loosely to prehistoric or early medieval earthworks that local tradition had long since disconnected from any specific history.

The earliest written reference to the feature comes from Charles Smith in 1815, who noted it in his survey of the county. Nearly a century and a half later, Seán P. Ó Ríordáin returned to the subject in 1932, recording the same tradition that a fort or enclosure of some kind had once occupied the site before the church was built upon it. The practice of erecting Christian buildings on top of earlier earthworks or enclosures was not unusual in Ireland; the raised, circular ground of a ringfort or enclosure offered a ready-made elevated platform, and such sites often already carried a degree of local significance. Whether the Coolfadda earthwork was a ringfort, a ceremonial enclosure, or something else entirely, is not established in the record. The church that now occupies the site is the only visible structure remaining.