The medieval parish church of Killossery, in north County Dublin, lost its baptismal font to Swords Roman Catholic Church at some point before living memory, leaving the shell of the building without even that basic furnishing. What remains on a low rise south of Rollestown Village, above the Broadmeadow river, is a plain rectangular ruin within a walled graveyard, quiet enough that it barely registers on most itineraries of the area.

The church itself is modest in scale, measuring thirteen metres in length and just under six metres wide, aligned east to west in the conventional manner of Christian worship. By the time of the Civil Survey of 1654 to 1656, it was already recorded as ruinous, which places its abandonment somewhere in the upheavals of the preceding century. A doorway in the western end of the north side wall once featured a round arch, noted as such by Walsh in 1888, though the arch itself is no longer intact. A single window in the east gable, widely splayed to draw in as much light as possible, once illuminated the interior. The east and west gables still stand to window height, while the north wall survives to between half a metre and one and a half metres. The south wall has almost entirely disappeared, leaving only faint traces in the ground.

The site sits on an elevation that gives it a certain quiet authority over the surrounding landscape, with the Broadmeadow river below. The walled graveyard that encloses the ruin remains the most intact element of the complex, and it is worth taking time to read the stones if they are legible. There is no elaborate visitor infrastructure here, which is rather the point. The surrounding area around Rollestown is agricultural and unhurried, and the church is the kind of place that rewards a slow approach on foot rather than a quick stop from a car. Those with an interest in the archaeology of the Fingal region will find it fits into a broader pattern of medieval parish churches that were already crumbling within a generation or two of the Reformation, their congregations dispersed and their fabric left to the weather.