The ruins in Raheny sit within an enclosing stone wall, and the interior floor level drops away sharply from the world outside, a fall of around 1.9 metres from the church to the footpath below. It gives the place a sunken, almost secretive quality, as though the building has slowly pressed itself into the ground over centuries, or the street has simply risen up around it and moved on.

The church is dedicated to St. Assin, and what stands today was rebuilt in 1712 on a site that was already considerably older. The fabric is rubble masonry, stones laid in random courses rather than regular rows, giving the walls a rough, uneven texture characteristic of early eighteenth-century vernacular building. Entry is through the west gable, and once inside the roofless shell, the east gable draws the eye immediately. It rises to a steep pitch and retains the remnants of a tracery window, the decorative stonework that would once have held leaded glass, cut from dressed limestone. The nave walls carry windows on both the north and south sides, though all are now headless, meaning the arched or flat stone lintels that spanned their tops are gone. There is also a blocked doorway at the western end of the north wall, an opening that once served some purpose and was later sealed, leaving only its outline in the masonry.

The ruins sit within the older part of Raheny village, enclosed by their stone boundary wall, and are visible from the street even if the interior requires a closer approach. The steep drop in level means that looking down into the nave from outside gives a different perspective than standing within it. The tracery remnants in the east gable are worth examining carefully, as dressed stonework of that kind tends to survive in fragments rather than as a complete composition. References in the historical literature go back at least to Walsh writing in 1888 and Appleyard in 1985, so this is a site that has been quietly noted by local historians for well over a century, even if it rarely figures in wider accounts of Dublin's architectural heritage.