A rath, to give the brief explanation it deserves, is a roughly circular earthen enclosure, typically dating from the early medieval period, built to define and protect a farmstead. They are common enough across the Irish countryside, but what makes this one at Granardkill quietly interesting is the suggestion that traces of domestic life survive within it, not just the enclosure itself.

The feature in question is a poorly defined, raised area measuring approximately three metres west-northwest to east-southeast and around 1.8 metres north-northeast to south-southwest. It sits in the north-eastern part of the rath's interior, and was first noted in 1975. Its shape is irregular, its edges indistinct, and any confident identification remains elusive. It may be the footprint of a house; it may be something else entirely, or simply a natural undulation in the ground. The date assigned to it is indeterminate, which is an honest acknowledgement that the archaeology has not yet yielded a clearer answer.