The ringfort at Bunnasillagh, in County Galway, belongs firmly to that category. A rath, as ringforts of earthen construction are sometimes called, would originally have been a circular or oval enclosure bounded by an earthen bank and ditch, serving as a farmstead and enclosure for livestock during the early medieval period. At Bunnasillagh, nothing of that remains visible. The site sits on a slight rise in low-lying grassland, which would once have made it a sensible, defensible position, but the ground today offers no trace of what stood there.

What keeps the site in the record at all is cartographic rather than physical. It was marked as 'Fort' on the Ordnance Survey Fair Plan, an early working document produced during the first systematic mapping of Ireland in the nineteenth century, and it subsequently appeared on the OS six-inch maps as an oval enclosure measuring roughly thirty metres north to south and twenty-five metres east to west. Those dimensions suggest a modest but fairly typical example of the form. Thousands of ringforts survive across Ireland in varying states of preservation, but a significant number, like this one, have been levelled by centuries of agriculture, drainage, and land clearance, leaving only their outline on older maps as evidence they existed at all.