The enclosure, roughly 23 metres by 21 metres and bounded by an earthen bank that barely rises above the interior ground level, looks from a distance more like a faint swell in the grass than anything deliberately constructed. Yet local tradition holds that three men are buried here, men lost by O'Sullivan Bear while attempting to cross the River Allow.

The name attached to the site, Cillin Una, is suggestive. A cillin is an informal or unconsecrated burial ground, typically used in Ireland for unbaptised infants or others excluded from churchyard burial, though this one carries a different and more historically charged story. The O'Sullivan Bear connection places it within one of the most dramatic episodes of late Elizabethan Ireland: the retreat of Donal Cam O'Sullivan Beare and his followers from Dunboy Castle in the winter of 1602 to 1603, a gruelling march northward through hostile territory in which the majority of those who set out did not survive. Whether the three men buried here fell during that crossing or at some other moment in that campaign is not recorded. O'Mullane, writing in the late 1970s, describes the place as a fort as well as a burial ground, and the earthen enclosure does share the oval morphology common to small early ringforts. The site appeared on the 1842 Ordnance Survey six-inch map as a clearly defined hachured oval, but by the 1905 and 1937 editions it was already marked as disused, its south-western arc cut through by a field fence. Approximately ten metres to the north-east lies a holy well, a proximity that is common enough in the Irish landscape to suggest the two features may have been understood as connected long before anyone thought to map them.