It sits slightly raised from the surrounding ground, measuring roughly 9.5 metres across its longer axis, and enclosed by a sod-covered stony bank that stands no more than 0.8 metres at its highest point. This is a barrow, a prehistoric burial monument, though time and agricultural activity have left it in a quietly ambiguous state. The bank's interior shows a broad slump, a depression caused by the gradual collapse of material inward, which may also include debris cleared from nearby fields over the centuries, making it difficult to read exactly what was once there.

Barrows of this kind are among the oldest human-made features in the Irish landscape, typically dating to the Bronze Age, though some have earlier or later origins. They were raised over the dead, sometimes containing cremated remains, grave goods, or cist burials beneath their earthen cores. What survives at Lismacbryan is modest but not isolated. Just 20 metres to the south lie the remains of a square enclosure, a separate but potentially related feature, suggesting that this particular stretch of ridge may have held some sustained significance for the communities who shaped it. The pairing of a round barrow with a square enclosure is not a common arrangement, and the proximity of the two is the kind of detail that tends to reward closer attention.