By 1902, the eastern bank had disappeared from the maps entirely, and by 1939 the process of erasure was well advanced. Today, the site is effectively gone at ground level, surviving only as a low swelling in the earth to the north, east, and west, barely enough to suggest that something once stood here.

What was here, before the land swallowed it, was a rath, the Irish term for a ringfort, the most common type of early medieval settlement in the Irish countryside. Ringforts were typically enclosed farmsteads, their circular earthen banks providing a degree of protection for a family, their livestock, and their stores. Tens of thousands once existed across Ireland; a great many have been lost to agriculture, drainage, and development over the past two centuries. The Lissard example followed a pattern familiar across the country: the 1842 Ordnance Survey six-inch map caught it more or less intact, but subsequent decades of farming steadily dismantled the banks, beginning with the east side and continuing until little remained above the soil.