This is a rath, the Irish term for a ringfort, the most common monument type in the Irish countryside. Thousands were built, mostly during the early medieval period, as enclosed farmsteads for a single family or small community. The earthen bank and external ditch, known as a fosse, defined the boundary of a household rather than a battlefield fortification.

This particular example at Knocknashannagh measures 38.5 metres across in both directions, making it a reasonably substantial specimen. It retains a double line of defence on its southern and eastern sides, with an inner bank rising 1.8 metres on the exterior face, a fosse between, and a second outer bank beyond that, standing 1.5 metres high. Two gaps break through the full circuit, one to the east and one to the northwest, each about four metres wide, connected by a rough trackway across the raised interior. Whether these openings are original entrances modified over time or later intrusions is difficult to say. What is recorded is that a quarter of the monument was knocked around 1928, a detail noted by Broker in 1937. The phrase is blunt and unsentimental, and the damage it describes was a common fate for such earthworks across Ireland during the twentieth century, when agricultural improvement took precedence over archaeological preservation. From its slope, the site commands wide views to the east, south, and south-west, a positioning that was almost certainly deliberate, offering both visibility and a degree of natural advantage to whoever chose the location.