The circular form recorded in 1838 belongs to a category of monument that would have been immediately legible to nineteenth-century surveyors but has since been swallowed entirely by the development that followed.

The evidence for this feature comes from the first edition of the OS 6-inch map, surveyed in 1838, which clearly marks a circular earthwork on land then belonging to Glasnevin House. Circular earthworks of this kind are a broad family in the Irish landscape, ranging from prehistoric enclosures to early medieval ringforts, the latter being enclosed farmsteads typically defined by one or more banks and ditches. The particular form here was recorded on a ridge top with a commanding view over the Tolka valley, a siting consistent with the way such enclosures were often positioned to take advantage of elevated ground. The site was compiled as part of a record by Geraldine Stout and uploaded in August 2011, drawing attention to what the historic cartographic record preserves even when the physical remains do not survive. The grounds are now occupied by St Mary's Secondary School.

Because there are no visible remains at ground level, a visit here rewards a particular kind of attention, one directed less at what can be seen and more at the landscape itself. Standing on or near the ridge, the view down towards the Tolka valley gives a sense of why this location was chosen, whether for settlement, enclosure, or something else entirely. The site is embedded within a functioning school campus, so access to the grounds is not straightforward, and any visit should be planned accordingly. The real value in knowing this place exists lies in understanding how thoroughly the urban fabric of modern Dublin has absorbed, and erased, layers of earlier occupation that the 1838 surveyors could still observe directly.