That it has survived at all, in a landscape long given over to farming, is part of what makes it worth a second look. The interior has been put to agricultural use at some point, as cultivation ridges running on a NNW-SSE axis make plain, yet the structure beneath and around them remains largely coherent.

This is a rath, the most common form of early medieval settlement in Ireland, typically dating from somewhere between the sixth and tenth centuries. A rath consists of a raised earthen bank enclosing a roughly circular area, with a fosse, or ditch, dug on the outside to supply the material for the bank. At Rathruane More, the enclosure measures approximately 35.5 metres north to south and 38.5 metres east to west. The bank is stone-faced on its inner side to a height of around 1.3 metres, and the stonework continues at the entrance, which faces south-south-east and is just under three metres wide, approached by a causeway crossing the fosse. A line of embedded stones runs along the outer edge of the bank from west to north-north-west. A second bank exists to the east and south-east, though whether this was part of the original design or a later addition is uncertain. More intriguing still is a possible souterrain in the interior. A souterrain is an underground passage or chamber, usually stone-lined, associated with early Irish settlement sites and thought to have served for storage, refuge, or both. Its presence here has not been confirmed, but the possibility adds a layer of complexity to what might otherwise read as a straightforward, if well-preserved, example of the type.