That small accident of topography is almost certainly why someone chose this spot to build an enclosure, and why what they built has survived at all.

The site at Fertiana is an oval earthwork, roughly 29 metres north to south and 40 metres east to west, which places it in the modest range typical of early medieval enclosures found across Ireland. These enclosures, often associated with farmsteads or minor ecclesiastical sites, were defined by combinations of banks and ditches, collectively providing a boundary that was as much a statement of territory as a practical barrier. At Fertiana, the southern side is marked by a scarp, essentially a cut slope in the earth, accompanied by a fosse, a term for the kind of flat-bottomed or V-shaped ditch commonly dug to define or defend a boundary. The eastern side carries a low bank, with a concentric ditch and field bank running alongside it. The dimensions are unspectacular in isolation, but the coherence of the layout, oval form, mixed earthwork techniques, and a deliberate relationship with the ridge itself, suggests careful, purposeful construction rather than incidental land management. Some quarrying has disturbed the north-western quadrant at some point, so that portion of the circuit is less legible than the rest.

What makes the setting genuinely interesting is the seasonal logic of the location. The surrounding terrain is marshy and floods in winter, meaning the ridge would have been effectively islanded for part of each year. That natural isolation may well have been a feature rather than an inconvenience for whoever occupied or used the site, offering a degree of security without requiring elaborate defensive works. The enclosure sits only around fifty metres back from the river, close enough to make use of it, but elevated just enough to remain above the waterline when the Suir spreads across the low ground.