Trees and rising ground limit the views outward, giving the place a quietly enclosed quality. What makes it worth pausing over is partly the physical fabric, sandstone walls built with some limestone and shale, a surviving buttress, a ruinous east gable with collapsed masonry heaped inside, and one intact window, a single-light flat-headed opening just one metre tall, still showing the holes where glazing bars were once fixed. A loose arch stone at the north-east corner of the graveyard is thought to be a remnant of the original doorway surround, the doorway itself now just a two-metre breach in the south wall. Higher up in the west gable, barely legible, are traces of what the historian Carrigan described in 1905 as a tall, very narrow window with an equally narrow splay. The church also retains a partial external base-batter, a sloped thickening at the base of the wall that helped transfer the load of the masonry outward and downward.

The building measures roughly 10.5 metres east to west and 4.25 metres north to south internally, an undivided single space of the kind common to medieval parish churches across Leinster. By 1640 it was listed, in the terrier accompanying the Down Survey parish map of Blackrath and St Martins, as consisting of little more than walls, with Sir Edmond Blanchfield recorded as the proprietor. The Down Survey, carried out between 1655 and 1656, also marks the church on its barony map of Gowran under the spelling Madackstowne. Carrigan, writing at the opening of the twentieth century, identified it as having been dedicated to the Blessed Virgin under the title of her Nativity, celebrated on the 8th of September, and noted that it served as the prebendal church of Blackrath, the parish now known as Maddockstown. A prebendal church was one whose income supported a cathedral prebendary, a cleric holding a stipend from the cathedral chapter, which in this case would have been the diocese of Ossory. Also associated with the site is an Ossory-type font, a category of carved stone baptismal basin particular to that diocese, now placed at the north-east end of the graveyard rather than inside the ruin itself.