A circular or near-circular enclosure wall around a burial ground is often a sign that something older underlies the site, the curve preserving the outline of an early medieval ecclesiastical enclosure long after the structures within it have disappeared.

Early Irish monasteries and church settlements were frequently enclosed within a roughly circular boundary, known as a cashel if built in stone or a rath-like earthwork if formed from a raised bank and ditch. These enclosures defined sacred ground, separated the religious community from the surrounding landscape, and often gave their shape to whatever came after them, including later graveyards, whose walls were simply built along the same line. The researcher Swan, writing in 1988, identified the circular form of the graveyard boundary at Fassagh as probable evidence of one such original enclosure, associating it with a nearby recorded graveyard site. It is a subtle kind of survival, with no arch or carved stone to draw the eye, just the arc of a wall following a logic set down perhaps a thousand years before anyone thought to document it.