What remains visible is little more than a curved arc of earthen bank sweeping from the south-east around to the south-west, the rest of the enclosure having faded into the field around it. That kind of near-invisibility is not unusual for a rath, the term used for an earthen ringfort of the kind built throughout Ireland roughly between the early medieval period and the early Christian centuries, typically serving as a defended farmstead for a single family or extended household. What makes Gorteenanillaun quietly remarkable is what survives within that eroded circuit.

Inside the interior of the rath lie two features of considerable interest. One is a children's burial ground, known in Irish tradition as a cillín, a type of unconsecrated burial site used for unbaptised infants and others excluded from churchyard burial, a practice that continued in rural Ireland well into the twentieth century. The other is a souterrain, an underground stone-lined passage or chamber, typically associated with early medieval ringforts and thought to have served for storage or as a place of refuge. The relationship between these two features is complicated by the fact that part of the souterrain actually overlies the enclosing bank itself, which raises questions about the sequence of construction and use across the site over what may have been many centuries. Whether the souterrain was inserted later, cutting across an already declining bank, or whether the bank had already partially collapsed by the time the passage was built, the stratigraphy points to a place that was returned to repeatedly and put to different purposes across time.