What looks at first glance like a walled graveyard on a quiet Kildare hillside is, on closer inspection, something considerably older reasserting itself through the grass. The enclosure at Kilrainy sits on a gentle east-facing pasture slope, and its outer boundary is a broad, flat-topped earthen bank, roughly 1.7 to 3.1 metres wide, that has been faced at some point with a mortared stone wall. That combination, ancient earthwork sheathed in later masonry, is characteristic of early ecclesiastical sites that remained in active use long enough to be tidied up by successive generations. Inside the bank, a path skirts the perimeter and may follow the line of an even older fosse, or defensive ditch. At the centre, the ground rises slightly into a roughly circular area of 18 to 20 metres across, defined by a low scarp, and it is here that a church and graveyard occupy what was probably the original sacred core of the site.

The overall shape of the enclosure, sub-rectangular on the outside but with a circular raised interior, reflects a pattern found at many early Irish ecclesiastical foundations, where a roughly circular temenos, or sacred precinct, was established first and later boundaries were adapted around it rather than replacing it. The whole enclosure measures about 47.9 metres east to west and 34.3 metres north to south, making it a modest but coherent example of the type. Mature chestnut and ash trees line the perimeter, and by 2005 aerial photography showed the site becoming considerably overgrown. Perhaps the most intriguing detail here is a bullaun stone recorded about 50 metres to the north-east of the main enclosure in 1985. Bullaun stones, boulders with one or more rounded depressions ground into their surface, are commonly associated with early Christian sites in Ireland, where they functioned variously as mortars, as receptacles for votive water, or simply as markers of long continuity of use. Its position just outside the enclosure boundary, rather than inside, raises quiet questions about how the original sacred landscape was arranged and what the stone was once understood to signify.