The enclosure measures thirty metres across and is defined by an earthen bank standing roughly 1.4 metres high, enough to have once marked a clear boundary between the domestic world within and whatever lay outside it. A later field boundary, running northwest to southeast, cuts across the southwestern side of the enclosure, the kind of casual truncation that happened across Ireland as agricultural patterns shifted and older boundaries were simply absorbed into newer ones.

This is a rath, the most common type of monument in the Irish countryside, built during the early medieval period, broadly between the fifth and twelfth centuries. A rath is essentially a raised earthen ringfort, a circular enclosure formed by one or more banks and ditches, typically used as a farmstead or the residence of a family of some local standing. What makes the Glenaglogh example quietly interesting is the possible presence of a souterrain in its interior. A souterrain is an underground passage or chamber, usually stone-lined, constructed beneath or adjacent to a ringfort. Their precise function is still debated, but they are generally understood to have served as cool storage areas, places of refuge, or both. The souterrain here has not been confirmed, which leaves the site carrying a degree of uncertainty that many more celebrated monuments do not.