The rath at Rath Beg sits in level pasture, in the south-east corner of a field, and offers no obvious trace of itself to anyone walking across it. It is the kind of site that exists more vividly on old maps than in the landscape itself, which makes it an interesting case of archaeology surviving almost entirely as cartographic memory.

A rath is an early medieval ringfort, typically a circular enclosure defined by an earthen bank and ditch, used as a farmstead or settlement. What survives here amounts to little more than a faint impression. Ordnance Survey maps from 1846 recorded a circular enclosure roughly twenty metres in diameter; by the 1894 revision, the same feature appeared as a roughly circular raised area of around fifteen metres. The reduction in apparent size between those two surveys suggests gradual erosion and agricultural pressure rather than any dramatic event. In the 1840s, Ordnance Survey field workers knew the site by the name Lisheengarriv, placing it on the eastern side of the townland, and described it as "a very small Danish fort 80 links in diameter," a period phrase using the old surveying unit of the link, equivalent here to about sixteen metres. The term "Danish fort" was commonly applied to ringforts in nineteenth-century Ireland, a folk attribution that had more to do with mythology than with Norse history; these sites are in fact of early medieval Irish origin. By the 1940s, the rath was recorded as part of Lawrence Kelly's land, one of two such features noted in the area at that time. Approximately thirty metres to the west, a group of standing stones occupies the same field, suggesting the wider landscape here carries several layers of human use across different periods. The views south towards The Paps of Dana, the twin hills associated in mythology with the goddess Anu, add a certain context to a site that is easy to miss but not, once known about, easy to forget.