This is a rath, the most common type of early medieval enclosure in Ireland, typically built as a defended farmstead for a family of some local standing. Thousands survive across the country in varying states, but this one at Ballinderry has been left largely to its own devices, its features now blurred by dense vegetation.

The enclosure measures approximately 60 metres on its northwest to southeast axis and around 40 metres across the other way, giving it a slightly compressed oval form. What defines it are three concentric elements: a scarp, which is an abrupt slope cut into the ground surface; a fosse, the ditch running between the inner and outer works; and an outer bank beyond that. Together these features represent a reasonably substantial earthwork, the kind that would have taken considerable communal labour to construct. The triple arrangement of scarp, fosse, and bank suggests the builders were serious about their enclosure, whether for the practical purposes of livestock management and defence, or as a marker of social prestige in early medieval Connacht.