What makes this particular ruin quietly odd is the layering of its own history: the original Mountstuart House recorded in the 1650s is now entirely lost beneath overgrowth to the north, while the standing remains belong to a separate, later building constructed sometime in the mid-nineteenth century, one that was already described as ruinous by the time the 1937 Ordnance Survey six-inch map was drawn.

The Down Survey, carried out between 1655 and 1656 under the direction of William Petty, was a systematic effort to map forfeited Irish lands following the Cromwellian settlement, and it shows two dwellings at this location. The survival of that cartographic record makes it possible to trace a site across three centuries of maps, even when almost nothing physical remains above ground. The extant brick structure, oblong in plan and running north to south, measures just over twenty metres in length and just under ten in width, with walls roughly forty-five centimetres thick. It was originally two storeys high, and a moulded brick cornice, a decorative projecting course that divided the two floors externally, once ran along its facade, with the top of that cornice finished in slate. Tall rectangular window openings, placed symmetrically one above the other, suggest a degree of formal intention in the design. There is evidence of a stone foundation beneath the brick. Crucially, this building does not appear on the first edition Ordnance Survey map, which rules out an earlier date and points to construction in the mid-nineteenth century.

The field is approached along what remains of a former avenue, still partially traceable. The original house site immediately to the north is heavily overgrown and not easily read on the ground, though a single standing pillar, possibly a remnant of the entrance to a yard, is visible among the vegetation. The surviving south wall and south-west corner of the brick building are the clearest things to look for. This is not a site with interpretation panels or managed access; it sits quietly in ordinary farmland, the kind of place that rewards a careful look at a map before arrival rather than an expectation of dramatic remains.