The oval rath at Knockaunabasty measures roughly 51.5 metres north to south and 33.5 metres east to west, but it announces itself only as a faint scarp in the grassland, its original earthen bank long since reduced to little more than a change in ground level. A rath is an early medieval ringfort, typically a circular or oval enclosure defined by one or more earthen banks and ditches, used as a farmstead or place of refuge. Here, the outline has been further compromised by a silage pit cut into the eastern interior and by quarrying activity in the north-west quadrant, which has left a rectangular hollow in the ground.

What makes this site linger in the mind is not the rath itself but what is associated with it: a children's burial ground. These sites, known in Irish tradition as cillíní, were used for the interment of unbaptised infants and others considered ineligible for consecrated ground, including stillborn children, and occasionally strangers or those who died by suicide. They occur across Ireland in great numbers, often attached to the margins of older monuments, ruined churches, or liminal landscape features, places that existed at the edges of sanctioned religious space. The association of a cillín with a pre-existing rath at Knockaunabasty follows a pattern found elsewhere in the country, where later communities returned to already-ancient enclosures for burial, drawn perhaps by a sense of the ground's prior significance, or simply by its position apart from ordinary use.