That is, in a sense, precisely the point. Somewhere in the gently undulating arable land of north County Dublin, a circular ring-ditch lies beneath the surface, invisible to anyone walking the fields. The only evidence of its existence is a crop mark, the kind of ghostly outline that appears in aerial photographs when buried features cause the plants above them to grow at slightly different rates, betraying the shapes of ditches and enclosures that have not been visible at ground level for centuries, perhaps millennia.

A ring-ditch is typically the buried remnant of a circular ditch, often associated with prehistoric funerary or ritual activity. In many cases these features represent the ploughed-down remains of a round barrow, where the outer ditch that once surrounded a burial mound is all that survives after generations of cultivation have levelled the earthwork above it. The Westpalstown example was identified through an aerial photograph held in the SMR file, with the record noted on the basis of a personal communication from T. Condit. The site was compiled by David O'Connor and updated by Christine Baker, with the record uploaded in December 2014. Beyond the crop mark itself and its location within arable farmland, little else has been formally documented about the site.

Because there are no upstanding remains, there is nothing to visit in any conventional sense. The fields around Westpalstown, a townland in the Fingal area of north Dublin, look much as any other stretch of intensively farmed land in the region. The real interest lies in what the aerial photographic record represents as a broader phenomenon: the sheer density of archaeological features across the Irish landscape that remain entirely below the plough-line, known only because a particular crop in a particular dry summer happened to grow unevenly over a ditch that nobody had seen for a very long time. For anyone curious about how archaeology is actually practised, that gap between what the photograph reveals and what the ground shows is worth thinking about.