It measures roughly 33 metres north to south and 43 metres east to west, and its existence is known almost entirely because aerial photography revealed what the eye on foot would easily miss. This is the kind of site that only becomes legible from above, where crop marks, soil discolouration, or subtle differences in vegetation growth betray the buried geometry of something much older.

Enclosures of this general type are common across the Irish midlands, though their individual histories vary considerably. Many are the remains of ringforts, known in Irish as raths, which were enclosed farmsteads used throughout the early medieval period, roughly between the fifth and twelfth centuries. Others may have served different purposes entirely, including ecclesiastical enclosures or earlier prehistoric boundaries. Without excavation, it is difficult to assign a firm date or function to the Killynan example. What aerial imagery captured in November 2005 was simply the outline, oval rather than the more typical circular form, suggesting either a deliberate design choice or the influence of the local topography on how the enclosure was laid out. The site was identified through Google Earth and Digital Globe aerial photographs, with the record compiled by Caimin O'Brien from details provided by Jean-Charles Caillère.