It has absorbed and straightened part of a much older enclosure, quietly repurposing early medieval earthworks into something a farmer could string a fence along. That kind of absorption is common enough across Ireland, but it makes reading the original form of a rath, a ringfort built from raised earth rather than stone, a matter of patient looking rather than obvious recognition.

The rath at Rathordan sits on a gently south-facing slope in improved pasture, and its overall shape is still traceable as a roughly circular area measuring approximately 22 metres north to south and 23 metres east to west. The enclosing bank survives in sections, most clearly from the south-east around through the south and south-west, where it still stands around a metre high on its outer face. A scarp, a deliberate slope cut into the ground rather than a built-up bank, carries the enclosure around from the west-south-west toward the north-east. Outside the bank there was once a fosse, the shallow surrounding ditch that would have added both drainage and a degree of defence; it has been backfilled over time, but its outline remains traceable, particularly around the north-east and south-east arcs where it curves back toward the modern field boundary. Two gaps in the enclosure have been noted, one at the north-west that may represent an original entrance roughly three metres wide, and a narrower break at the south. Ringforts of this kind were typically built and occupied during the early medieval period in Ireland, broadly between the fifth and twelfth centuries, and served as enclosed farmsteads for a family and their livestock rather than as military fortifications in any strict sense.

The eastern arc, where the old bank has been incorporated into the modern field boundary and its curve straightened into a rectilinear line, is worth examining closely. That edit, made at some unknown point by someone with entirely practical intentions, is itself a small document of how the Irish landscape layers one era's use on top of another's.