Part of its bank has been absorbed into the surrounding field fence system, so a casual eye might miss the fact that what looks like a field boundary is actually the surviving edge of an early medieval settlement enclosure, probably more than a thousand years old.

This is a rath, the most common type of ringfort in Ireland, built as a defended farmstead by enclosing a circular area with an earthen bank and a fosse, which is a shallow external ditch that provided both the material for the bank and an additional obstacle. At Mountmusic the enclosure measures roughly 33 metres east to west and 30 metres north to south. The bank survives to a height of about 1.4 metres along the northern and eastern arc, accompanied by a fosse approximately 0.6 metres deep. On the eastern to south-south-western side the bank has given way to a scarp, a sloped face of earth, standing 2.25 metres high, which may reflect the natural topography of the hillside working in combination with the original construction. Elsewhere the perimeter is marked only by a low grass-covered rise, barely 0.6 metres above the interior. The interior itself slopes gently downward toward the south-east, following the natural lie of the hill. Thousands of such raths are scattered across Ireland, and they are generally dated to the early medieval period, roughly the fifth to the twelfth century, serving as the enclosed homesteads of farming families rather than as military fortifications in any conventional sense.