Yet that modest strip of repointed masonry carries a surprisingly dense history, and the slight artificial rise to its west, easily mistaken for a natural undulation in the ground, marks where a residential tower once stood, the kind of structure in which a priest or caretaker might have lived, now entirely levelled. A gap in the wall near its western end, with a rebate still visible, is thought to indicate the position of the original church doorway. The modern St Joseph's Catholic Church stands just to the northeast, making this one of those quietly layered Irish sites where the medieval and the contemporary share a boundary wall.

The church's documented past stretches back at least to the early thirteenth century. Around 1212, Archbishop de Loundres granted Ballymadun church to the Augustinian nunnery of Grace Dieu, an exchange arranged in compensation for St Audoen's in Dublin, which the nuns had previously held under an earlier grant from Archbishop Comyn. The church was dedicated to All Saints and included a chapel of the Blessed Virgin, as well as an annexed chapel at Boraneston. Unusually, an anchoress, a religious woman living in permanent enclosure, had a cell here, and when the Grace Dieu prioress took on the parish, she was bound to pay certain chief rents to this anchoress. The ecclesiastical taxation of 1302 to 1307 assessed the church at 20 marks. In 1237, the wider manor of Ballymadun passed to Ralph de Turberville by crown grant, at the notable annual rent of one pair of gilt spurs. The manor changed hands repeatedly over the following centuries, passing through the de la Hoyde, Mortimer, Preston, and Gormanstown families. By 1615, a royal visitation found the chancel already in ruin; by 1630, Archbishop Bulkeley's surveyors noted the entire church as ruinous, the chancel down, and lacking all ornaments, though a vicar, one William Tedder, was still in post.

The site is located in the townland of Glebe, near Garristown in north County Dublin. The ruins sit within a walled graveyard that remains in use, so the ground is managed and reasonably accessible. The low wall is easy to walk past without registering its significance; it is worth pausing at the western end to look for the doorway rebate, and at the grassed mound just beyond the wall where the tower once stood. When the antiquarian Walsh visited in 1887, he could still trace the full outline of the nave, some 15.5 metres by 9 metres, and the chancel beyond it. Today that outline has largely disappeared back into the earth, and the south wall is all that breaks the surface.