The enclosure at Dundonagh measures roughly 46 metres east to west and just over 42 metres north to south, making it a substantial ring fort, the kind of enclosed farmstead or defended homestead that once formed the basic unit of rural settlement across early medieval Ireland. What makes it worth a second look is how much of its original form survives: a slight earthen bank or scarp still rises to about 1.8 metres on the eastern side, and outer facing stones remain visible along the perimeter, suggesting the bank was once more formally revetted.

The site has two entrances, one at the north-west and one at the north-north-east, though the latter, about 4.5 metres wide at the top, is considered the more likely original opening. Ring forts, known variously as raths or cashels depending on whether they were built from earth or stone, typically had a single entrance oriented away from prevailing weather or towards a particular track or boundary, so the survival of what may be the original gap gives a small but genuine sense of how the enclosure was meant to be approached and used. The hedge that now follows the line of the bank is a later addition, but it has probably helped preserve the underlying earthwork from more serious disturbance.