The one at Doonis is a rath, a type of ringfort that would once have served as a defended farmstead during the early medieval period, its circular earthen banks enclosing a domestic space for a family of some local standing. What survives here is a large circular area, approximately 34 metres across on its northeast to southwest axis, defined by two low banks of earth and stone with a shallow fosse, the term for a ditch, running between them, and a further shallow fosse outside the whole arrangement.

The site commands wide views across an arc from east to south to west, which tells you something about why it was placed here. Early medieval farmers and their households were not indifferent to prospect; a south-facing hillside offered both warmth and visibility, useful qualities whether you were watching livestock or watching for trouble. The double-bank arrangement is worth noting. Many raths have a single enclosing bank, so the presence of two concentric banks with an intervening fosse suggests this enclosure may have belonged to someone of slightly higher rank or greater resources, though the outer bank has been considerably reduced over the centuries and now survives as little more than a scarp on the eastern and western sides. The inner fosse is in better condition towards the north. The interior itself slopes noticeably from north-northeast down to south-southwest.

Modern agricultural activity has left its mark. A field fence running northwest to southeast bisects the interior of the monument entirely, and another runs east to west roughly along the line of the outer bank, so the original form of the enclosure requires some imagination to read on the ground. The companion ringfort, a distinct and separately recorded monument, sits just a short distance to the northeast.