What they found was a burnt mound, one of the most common yet persistently puzzling monument types in the Irish archaeological record. These sites, known in Irish as fulachtaí fia, typically consist of mounds of fire-shattered stone and charcoal-rich soil accumulated around a trough, and while it is widely accepted that they involved the repeated heating of stones and their use in boiling water, their precise purpose remains debated. Cooking, bathing, brewing, and industrial processes have all been proposed over the years, often with considerable conviction and equally considerable disagreement.

The Roganstown example came to light not through dedicated survey but through the pressure of development. Excavated under licence number 09E0465, the site was uncovered in advance of a golf course development, a circumstance that has revealed a great many archaeological sites across Ireland since planning regulations began requiring pre-construction investigation. The burnt spread measured roughly 3.6 by 5.6 metres and lay within a natural depression approximately 0.37 metres deep. Within that hollow, excavators recorded charcoal-rich silts mixed with inclusions of fire-cracked limestone and sandstone, the characteristic debris left behind when stones are repeatedly heated and then plunged into water, causing them to fracture and eventually become useless for further heating. The findings were documented by Dehaene in 2003 and later compiled by Christine Baker for the Irish archaeological record.

Roganstown itself sits in north County Dublin, a quietly rural area despite its proximity to the city's expanding commuter belt. The site is not publicly accessible in any formal sense and does not have a visitor arrangement or interpretive signage, as is the case with the vast majority of excavated fulachtaí fia, which are recorded, backfilled, and returned to the landscape. What the Roganstown burnt mound offers, then, is less a destination than a prompt to look differently at the ordinary countryside, to notice the low-lying damp ground and shallow depressions that these sites favour, and to consider how intensely used and repeatedly visited such apparently unremarkable spots once were.