It is not much to look at now, which is precisely what makes it worth knowing about. The earthwork measures roughly 27 metres north to south and just under 21 metres east to west, and what survives is partial: a bank curving from the east through the south to the northwest, and a fosse, the external ditch that would have reinforced the enclosure, running from the south around to the west. The rest has been absorbed, gradually, into the working landscape around it.

This is a rath, the most common type of ringfort in Ireland, a class of enclosed farmstead built predominantly during the early medieval period, roughly between the fifth and twelfth centuries. Constructed from earth rather than stone, raths were the everyday settlements of farming families across the island, though their banks and ditches also carried social meaning, marking out territory and status. Thousands survive across Ireland in varying degrees of completeness, and thousands more have been ploughed away or built over entirely. The one at Glennagarraun sits in the poorly preserved category, its original form discernible but diminished, its circuit no longer whole.