That particular category of absence is more common in Ireland than one might expect, but it still carries a certain weight: a place that was significant enough to survive from early medieval times into living memory, then quietly erased within a generation.

Ringforts, the enclosed farmsteads of early medieval Ireland typically defined by one or more earthen banks and ditches, were once so numerous across the island that they shaped the rhythm of the landscape. This one at Willowbrook sat on a gentle south-facing slope in undulating pasture, modest in scale at roughly twenty metres in diameter. It does not appear on the first detailed Ordnance Survey mapping of the area, the six-inch series published in 1837, though its absence there may reflect the limitations of that survey rather than the fort's non-existence. By the 1912 revision, it appears clearly, rendered as a roughly circular hachured outline, the cartographic convention for an earthwork of raised or depressed ground. Sometime in the 1940s, according to local knowledge recorded in the Sites and Monuments Record, it was levelled. The land was pasture then and presumably remained so; the fort simply became inconvenient.