Within this wider site, a geophysical survey has quietly mapped something easy to overlook on paper but harder to dismiss in context: a modest oval enclosure, roughly 42 metres east to west and 30 metres north to south, bounded by what appears to be a narrow ditch or palisade trench. A palisade trench is the cut left in the ground by a row of upright timber posts set close together to form a defensive or enclosing barrier. It is an unremarkable type of feature in itself, found on sites across prehistoric Ireland, but at Drumanagh, the wider circumstances give it a particular weight.

The survey was carried out under Licence no. 12R127 by the Discovery Programme, the Irish state body responsible for large-scale archaeological research, as part of its project examining Late Iron Age and so-called "Roman" Ireland. That framing matters. Drumanagh has long attracted speculation about possible Roman-period contact or activity on the island, and the project was designed to bring systematic, evidence-based investigation to bear on such questions. Within the enclosure, the eastern half shows geophysical signals consistent with burnt material, though what generated that burning remains uncertain. Two breaks in the enclosure boundary, each around five metres wide, occur on the north-east and south-east sides and are interpreted as likely original entrances. The north-east entrance is particularly notable: it appears to be flanked by pit-type features, possibly post-pits, which would suggest a more deliberate, structured threshold, perhaps with a gated or framed opening, rather than a simple gap in the perimeter.

The headland at Drumanagh is privately farmed land, and public access to the site itself is not guaranteed. The enclosure identified through the geophysical survey is not visible on the surface in any meaningful way; what was found was detected through ground-penetrating and magnetic survey methods rather than upstanding remains. Visitors to the area can view the headland from the coastal path near Loughshinny, and the surrounding landscape gives a reasonable sense of the exposed, sea-facing position that made this promontory significant across many centuries. The site's interest lies less in what can be seen and more in what the subsurface evidence, carefully read, continues to suggest about activity here during a period when Ireland's relationship with the Roman world remains genuinely unresolved.