What makes it unusual is not what is known about it, but how little: a name, a tree, and a coordinate that no researcher has since been able to pin down with any confidence.

The Civil Survey, carried out between 1654 and 1656, was commissioned by the Cromwellian administration to establish a detailed account of landownership and property across Ireland, largely as a prelude to the redistribution of land following the wars of the 1640s. It recorded Killossery House and, notably, a tree associated with it, suggesting a property of some standing in the landscape. A named tree beside a named house was not a trivial detail; in a period when timber was a valued resource and landmark trees often served as boundary markers or gathering points, the pairing implies a place that was locally recognised and worth distinguishing. The entry was compiled as part of the broader record for County Dublin, and has been noted by Geraldine Stout, who uploaded the record to the Irish historic sites database in August 2011. Beyond this single reference, the precise location of the house has not been established.

Killossery is a small rural townland, and anyone visiting the area today will find a quiet agricultural landscape with little to guide them toward a specific spot. There is no ruin, no visible earthwork, and no commemorative marker recorded in association with this site. The value of the place, such as it is, lies in the act of looking rather than finding: walking the townland with the knowledge that a house and its tree were here in the mid-seventeenth century, named and counted at a moment of profound upheaval in Irish history, and that both have since disappeared so completely that even the ground they occupied remains uncertain.