The fact that a church was constructed within such an enclosure, rather than beside or around it, speaks to the layered and sometimes pragmatic way that religious communities in rural Ireland made use of whatever landscape was to hand. What makes the detail more striking still is that the chapel's own walls were pushing against that ancient boundary: the external south-east corner of the building cuts directly into the enclosing bank of the rath.

By the time the Ordnance Survey recorded the site in 1838 on its first six-inch map, the chapel was already marked as a ruin, noted as an L-shaped structure named Mountcross R.C. Chapel. The cartographic evidence places its construction somewhere in the 18th or 19th century, which would situate it firmly in the era of the Penal Laws and their aftermath, when Catholic worship in Ireland was variously suppressed, tolerated, and eventually restored. What survives today is sparse: a section of the east wall, standing to roughly 1.5 metres, built in drystone masonry with no mortar, and now heavily colonised by ivy; and the grassed-over foundation line of the south wall, barely 30 centimetres above ground and packed with rubble at its western end. No architectural features remain. A 20th-century headstone has been incorporated into the north end of the east wall, a quiet indication that the associated graveyard was still in use long after the chapel itself fell silent. Some overgrown wall-footings nearby are more probably grave kerbing than any remnant of the chapel's north wall.