Ring barrows are prehistoric funerary monuments, typically Bronze Age, consisting of a low central mound or flat interior enclosed by a circular ditch and an outer bank. The example at Barnanalleen is modest even by the understated standards of this monument type, but its survival in a working agricultural landscape gives it a particular kind of interest.

The structure measures roughly 4.75 metres north to south and 5.25 metres east to west across its interior, defined by a fosse, or enclosing ditch, that is best preserved along its north-eastern to western arc, where it reaches a width of around 2.4 metres. The outer bank, which would once have given the monument a more pronounced profile, has been almost entirely levelled, its interior height now only around ten centimetres above the surrounding ground. That gentle depression and slight rise in the pasture, barely perceptible underfoot, is what remains of a burial monument that was already ancient when the first Christian monasteries were being founded in Ireland. A tertiary road runs about forty metres to the south-east, which suggests the site has long sat at the quiet margin of whatever activity shaped this part of Tipperary.