It leaves no mark on the surface, no earthwork, no ring of stones. Its outline exists only as a cropmark, the kind of shadow that dry summers burn into cereal crops when the soil above a buried ditch retains slightly more moisture than the ground around it, causing the plants above to grow fractionally taller or greener. Seen from above on aerial photography, the shape resolves clearly: a nearly circular enclosure roughly 26 metres north to south and just over 24 metres east to west, defined by a continuous ditch about a metre wide running almost the full circuit of the site.

What makes the Tinakelly enclosure quietly thought-provoking is that detail about the entrance, or rather the absence of one. No definitive gap has been identified in the ditch, which is unusual. Enclosures of this general type, ringforts and related forms widespread across early medieval Ireland, typically have a clear break where a causeway or entrance passage allowed access. Without one, the function and date of this particular feature remain open questions. The site sits in low-lying ground at around 21 metres above sea level, roughly 1.7 kilometres from the Irish Sea coast to the east, with the landscape rising gently toward Tinakelly House on a low hillock to the east, and falling back toward Rathnew to the southwest. Less than 600 metres to the south-southwest, the ruined church and oval-walled graveyard at the historic centre of Rathnew form another cluster of early ecclesiastical remains, suggesting this corner of Wicklow has a longer settled history than its present agricultural fields might imply.

The enclosure itself is not visible at ground level, so a visit to the field would reveal nothing without prior knowledge of where to look. The cropmark is most legible in aerial images taken during dry periods in summer, when the buried ditch shows up most sharply against the surrounding crop.