What makes this particular rath worth a second look is not just its survival but the combination of its defences and what lies beneath it: a souterrain, an underground stone-lined passage or chamber, sits just south of the rath's centre, hinting at a more complex domestic life than the grassy banks alone suggest.

Raths, also called ringforts, were the dominant form of rural settlement in early medieval Ireland, roughly from the sixth to the twelfth centuries, and they functioned primarily as enclosed farmsteads rather than military fortifications. The one at Garryletter is roughly circular, measuring 23 metres north to south and 20 metres east to west. It is defined by a substantial scarp, a steep earthen slope, rising to 3.6 metres, with an intervening fosse, that is, a ditch, some 3 metres wide, and an outer bank visible on the western to north-eastern arc. That outer bank, though only 0.3 metres on its inner face, rises to 4.6 metres on its exterior, giving some sense of the effort that went into its construction. A formal entrance, 3 metres wide, faces south-east. The souterrain beneath the interior would have served for storage, possibly for dairy produce, and may also have offered a refuge in times of threat, a feature found at a number of Kerry raths but always worth noting when it survives.