It is not especially large, measuring roughly 14.5 metres along its north-east to south-west axis and only 5.5 metres across, rising to a height of just 0.8 metres. What makes it quietly arresting is its shape: subrectangular rather than the rounded form more commonly associated with natural rises or field spoil, and with a noticeably well-defined slope leading up to a relatively flat top. That combination of deliberate geometry and modest scale suggests a human origin, though precisely what purpose it served remains unrecorded.

Mounds of this kind are scattered throughout the Irish landscape and resist easy classification. Some are the eroded remains of mottes, the raised earthen platforms associated with early Norman fortification. Others are the remnants of much older funerary or ceremonial monuments. Without excavation, the Castlewarren example holds its purpose quietly to itself. The surrounding land, described as fairly poor pasture, gives little away, and the sole modern intrusion on the scene is a telegraph pole standing immediately to the north-east, lending the mound an oddly companionable neighbour across the centuries.