A rath, to use the Irish term, is a roughly circular or oval earthen enclosure typically built between the sixth and twelfth centuries, used as a farmstead and defended by one or more earthen banks and ditches. What makes this particular site notable is not what survives but what the cartographic record reveals about what has been lost.

When the Ordnance Survey produced its six-inch map in 1838, the site was recorded as a roughly subrectangular enclosure measuring approximately 43 metres from east-northeast to west-southwest and around 34 metres north to south. Marked within the northern sector of that enclosure was a feature noted simply as a 'Cave', a designation the surveyors of that period used for souterrains, the stone-lined underground passages associated with ringforts that were used for storage or refuge. By the time the 1933 edition of the same map was produced, the enclosure itself had vanished from the record, leaving only a curving field boundary running from northwest to southeast. When the site was inspected in May 1983, that curving boundary was all that remained visible on the ground, and even then its significance was uncertain; it may simply reflect the former line of the rath rather than preserve any original earthwork.

The trajectory here is a familiar one in the Irish midlands and west, where agricultural improvement from the eighteenth century onwards saw ringforts levelled, their banks spread to feed the surrounding land. What lingers at Ballyshea is a single arc in the field pattern, the kind of detail that is invisible unless you know to look for it.