What was once a defended farmstead of the early medieval period, a rath being the Irish term for a roughly circular enclosure bounded by one or more earthen banks and ditches, now survives principally as a cropmark, the kind of ghostly outline that appears in aerial photography when buried ditches affect the growth of crops above them.

The enclosure at Killesk is bivallate, meaning it was originally defined by two concentric rings of bank and ditch rather than one. Its interior measures roughly thirty metres in diameter, with the outer extent reaching approximately forty-five metres across. Aerial photographs have revealed an entrance gap cutting through both ditch features at the south-south-east, a detail that gives some sense of how the original occupants moved in and out of the enclosed space. The cropmark appears across several sets of aerial imagery, including Ordnance Survey photographs from 2000, digital aerial surveys from 2006, and, more faintly, on Google Earth imagery from 2005.

Because the site exists almost entirely as a subsurface feature, there is little to see at ground level. Its interest lies in what the aerial record has preserved rather than in any visible earthwork, making it the kind of place that rewards knowing what to look for, even if what you find is largely the outline of an absence.