The rampart has been levelled, yet the circular area it once enclosed, roughly 31 metres across, still betrays itself through a difference in the colour of the pasture growing over it. This phenomenon, sometimes called a cropmark or soilmark effect, occurs when buried features alter the moisture or nutrient content of the soil above them, causing the vegetation to respond differently to drought or seasonal change. It is one of the quieter ways that the past refuses to stay hidden.

A ringfort, or rath, is the most common archaeological monument type in Ireland, typically a circular enclosure defined by one or more earthen banks and ditches, and used during the early medieval period, roughly the fifth to twelfth centuries, as a farmstead or place of settlement. The Knockburden example appeared on Ordnance Survey six-inch maps in 1842, 1903, and 1940, each time depicted as a hachured circular enclosure of around 35 metres in diameter, suggesting it remained at least partially upstanding across that century. By the time P. J. Hartnett recorded it in 1939, the rampart still stood seven feet high, and the site retained a causewayed entrance to the south-west, a deliberately raised crossing over the enclosing ditch that would have served as the main approach. Hartnett also noted two additional gaps cut into the earthwork, made, as he put it, to facilitate agricultural operations. Those practical breaches, meant to allow machinery or livestock through, were likely the beginning of the end for the physical structure. At some point after that 1939 account, the rampart was levelled entirely.