Drumlins, those elongated egg-shaped hills formed by glacial activity and so characteristic of the Ulster landscape, were favoured spots for early enclosures, offering natural elevation and visibility over the surrounding terrain. The fort at Listraheagny occupies exactly this kind of position, though what you encounter today is a monument considerably reduced from whatever it once was.

The enclosure measures approximately 24 metres north-northeast to south-southwest and just over 21 metres across the opposing axis, making it a modest but well-defined subcircular space. An earthen bank surrounds it, overgrown and eroded, but still reaching an external height of nearly three metres on the western side. A fosse, the external ditch that typically accompanies such enclosures, survives in trace form on the west, its base around a metre wide and its depth now quite shallow. On the south-southwest, the bank incorporates an outer stone facing, suggesting at some point the structure was adapted or reinforced when a field boundary was built against it, absorbing part of the monument into the working agricultural landscape. The northeastern quadrant of the site has been quarried away, removing a significant portion of the original bank. This loss is not merely aesthetic. Because no entrance survives elsewhere around the perimeter, it is plausible that the original approach to the enclosure lay precisely in that damaged section, meaning the quarrying may have destroyed the one feature that would have told us most about how people moved into and out of the place.