What the cartographers overlooked, aerial photographers eventually caught: a shallow bank and accompanying fosse, or external ditch, tracing an arc across a flat field in Doonvullen Upper, its outline only fully legible from the air.

The enclosure was first formally identified during the Bruff aerial photographic survey in 1986, recorded as reference Bruff 18002 on AP 4/3689. A decade later, in 1996, the Discovery Programme confirmed the finding through the McCloud photographic survey, establishing the site's dimensions as roughly 40 metres north to south and 32 metres east to west. The structure itself consists of a crescent-shaped area defined by a low bank approximately 5.5 metres wide, with an external fosse around 3 metres across. Enclosures of this general type, broadly circular or oval earthworks defined by a bank and ditch, are found widely across Ireland, often interpreted as early medieval farmsteads or stock enclosures, though without excavation it is rarely possible to say more than that. What is more unusual here is the company the site keeps: a second enclosure adjoins it on the western side, another sits immediately to the north just across the townland boundary with Doonvullen Lower, and a third lies only 30 metres to the south. That boundary line, separating Doonvullen Upper from Doonvullen Lower, actually clips the northern edge of the site, suggesting the modern administrative division was drawn with some awareness of the earthwork's presence, or simply that older landscape features persisted long enough to shape later boundaries.

The site sits on gently waterlogged ground with open views in most directions, though a hill to the east interrupts the sightlines on that side. Because the bank is low and the surrounding pasture is flat, the enclosure is not straightforward to read at ground level. Aerial imagery offers the clearest view: it appears on Ordnance Survey orthoimagery from 2005 to 2012 and is faintly discernible on a Google Earth image taken on 28 June 2018. Anyone visiting should come prepared for soft, potentially wet underfoot conditions, and would benefit from studying the aerial imagery beforehand to orient themselves to the crescent's shape before setting foot in the field.