The enclosure measures approximately 170 metres north to south and 140 metres east to west, which makes it a substantial feature, roughly the size of several football pitches, yet it sits in ordinary rolling farmland without any particular fanfare. What makes it quietly unusual is the way its boundary shifts in character as it circles the site: in some sections an earthen bank and external fosse, a ditch dug to reinforce the perimeter, define the edge clearly, while elsewhere the ground simply drops away in a natural scarp, and along part of the circuit a stream has been absorbed into the monument's boundary, doing the work that a dug fosse might otherwise do.

Ecclesiastical enclosures of this type are associated with early Christian foundations in Ireland, where a roughly circular or oval boundary, sometimes called a vallum, separated the sacred precinct of a monastery or church from the surrounding landscape. The enclosure at Cloondergan is recorded as being in fair condition, with the bank and fosse best preserved along the southern arc from south-east through to south-west. Inside, in the north-eastern quadrant of the interior, the remains of a church survive alongside a feature recorded as a cillin burial ground, a term used in Ireland for informal burial sites, often associated with unbaptised infants or those excluded from consecrated ground, though the designation here simply indicates a small graveyard connected with the ecclesiastical site. The presence of both a church and a burial ground within a defined enclosure suggests a community of some longevity and organisation, even if the historical record of who founded or maintained this particular settlement has not come down to us.