The problem is that nobody has been able to say exactly where. A low, wide rise of ground to the west of the present house is marked by faint earthen banks and shallow depressions; these slight traces are the best candidates for what survives of an early seventeenth-century complex that was, as of 1659, still described as being in good repair.

The evidence comes from the Down Survey, a remarkable mid-seventeenth-century mapping project that recorded Irish land ownership in extraordinary detail following the Cromwellian conquest. Its accompanying terrier, a written description of the mapped features, noted plainly that there was a house with a bawn in Heathstown in good repair, and the map itself depicted a two-storey structure with a gable-ended chimneystack set within a rectangular bawn, the type of walled or earthen enclosure that was a standard feature of plantation-period settlement in Ireland. The property is identified as belonging to Andrew Tuite, whom the same terrier labels an Irish papist, the blunt administrative shorthand of the period for a Catholic landowner. The Down Survey places the complex close to the eastern boundary with the neighbouring townland of Dervotstown, and the present Heathstown House sits approximately 440 metres west of that boundary, which puts it in plausible proximity, though no dressed stonework of sixteenth or seventeenth-century character has been found either in the house or its yard. The existing house dates to 1834, a date recorded on a weather vane.

What remains visible on the ground is frustratingly subtle. The low rise to the west of the 1834 house is bounded by marshy ground to the west and south-west and by a gentle scarp running from south to east. Very slight banks cross the rise, and depressions at its south-eastern and northern ends are the features most likely to correspond to the footprint of Tuite's vanished house. It is the kind of site where knowing what to look for matters almost as much as looking.