What gives the site its quiet strangeness is that those earlier layers have not entirely disappeared. Beneath the sycamore trees in the northern part of the graveyard, the earth rises noticeably, forming a raised platform roughly 1.1 metres high. This earthwork is the surviving arc of an early ecclesiastical enclosure, the type of roughly oval boundary, usually of earthen construction, that typically defined an early Irish monastic or church site. The Ordnance Survey six-inch map of 1936 records the full oval shape around the present church, approximately 55 metres long and 46 metres wide, and parts of its line are still readable in the graveyard wall built in 1712 along the eastern side and continuing to the southwest.

The history of this site runs back at least to the sixth century, when it was associated with a figure known as St Pappan, after whom the current church is named. In the late twelfth century, a formal medieval parish church was erected here by Adam de Fiepo, who subsequently granted it to St Mary's Abbey in Dublin, one of the most powerful Cistercian houses in medieval Ireland. By 1615, when the Regal Visitations surveyed the state of churches across the country, the building was already described as ruinous. The 1709 structure replaced whatever remained, and almost nothing of the medieval church survives above ground. The single exception is a stone font, now sitting in the southwest corner of the chancel, which is the only tangible remnant of de Fiepo's foundation. A holy well associated with the early site also lies close by. The raised enclosure itself was cut through at some point by the insertion of the Domville family tomb, a reminder that even archaeological traces are not immune to later interventions.

Santry is now well within the northern suburbs of Dublin, and the churchyard is not difficult to find, though it sits at some remove from the noise of the surrounding roads. Visitors who look carefully at the northern section of the graveyard will notice the change in ground level where the old enclosure bank survives, marked by the line of sycamores. The font inside the church is worth seeking out if access is possible. A holy well associated with the early foundation is recorded nearby, though its exact condition and accessibility may require some local enquiry.