The oval, flat-topped earthwork at Ballytarsna sits on wet, poorly drained ground in County Tipperary, pressed between a working quarry to its northwest and the main Dublin to Cork road to its southeast. It measures roughly thirteen metres east to west and seven metres north to south at its base, rising to between one and one and a half metres in height, and it is defined by a scarp, the steep outer edge that gives the mound its shape. A post-and-wire fence bisects it to the south. Road-building material has been dumped across its southwestern end. Whatever its original extent, centuries of incremental interference have made that question very difficult to answer.

The mound's age and original purpose are not recorded, but earthen mounds of this kind in Ireland range from prehistoric burial monuments to early medieval assembly sites or territorial markers, and the presence of an outer fosse, a shallow defensive or defining ditch, hints at something more deliberately constructed than a field clearance heap. A sketch plan and section drawn in 1954 recorded a short length of that outer fosse surviving in the southeastern sector, which is the only surviving measured record of the monument in anything approaching its earlier condition. By then, damage was already well underway. The first edition Ordnance Survey six-inch map of 1843 shows a small quarry immediately to the southeast of the mound, in the very area where the road now runs, meaning that quarrying and road-making have together consumed whatever originally lay on that side.