The one at An Garrán, in the valley of the Milltown river in Co. Kerry, breaks that pattern entirely. It occupies level, marshy ground on the valley floor, an unusual choice that sets it apart from the usual upland raths scattered across the Dingle Peninsula.

The site is bivallate, meaning it is enclosed by two concentric earthen banks and their corresponding ditches, known as fosses, rather than the single bank more commonly seen. Both banks are now densely overgrown, and the interior holds what appear to be the remains of animal pens, suggesting the enclosure served an agricultural function as much as a defensive one. There is also a large hole in the interior that may indicate a souterrain, an underground stone-lined passage or chamber typically used in early medieval Ireland for storage or as a place of refuge. A causeway crosses the outer fosse on the southern side, though whether this marks the original entrance to the site remains uncertain. That uncertainty is not simply a matter of time and decay; when J. Cuppage's archaeological survey of the Dingle Peninsula recorded the site in 1986, the survey team were refused access by the landowner, meaning the published account rests on no more than a brief external examination. The rath carries a preservation order under the National Monuments Acts, but it has never, as far as the record shows, been formally investigated from the inside.