That alone tells you something has gone quietly wrong with this building's story. What survives on the flood-plain of the River Blackwater in County Meath, roughly 240 metres south-west of a distinctive bend in the river, are two opposed corners of a structure measuring approximately nine metres by eight, split apart by the later boundary wall of the Headford estate. Despite that indignity, the fabric retains enough detail to read: a corner fireplace at the west angle, a ground-floor doorway near the east angle of the south-east wall, wall rebates that once supported first and second floors, a window embrasure at first-floor level, and a parapet with long narrow slits, now blocked. The 1835 edition of the Ordnance Survey six-inch map labels it in gothic script as an Old Castle, which is the cartographers' way of signalling something already ancient and ruined. It is a designation that raises more questions than it answers.

The land here belonged, before the Reformation, to the Knights Hospitaller, the military religious order whose Irish headquarters lay at Kilmainham in Dublin. This particular holding was a grange, meaning an outlying agricultural estate managed on behalf of the mother house, supplying it with produce and revenue. The grange at Kilmainhambeg in Kells parish was surrendered to the Crown in 1541, part of the general dissolution of monastic and religious properties under Henry VIII. Whether the structure at this location served as the caput, the administrative and residential centre of that grange, is not established, but it remains a genuine possibility. A gabled house in this vicinity appears on the Down Survey maps of the mid-seventeenth century, those systematic land surveys carried out under Cromwellian administration, and the surrounding townland is recorded as being held in 1640 by four proprietors: Nicholas Barnwall of Turvey, Richard Ledwitch of Cookstown, Robert Beg of Navan, and Patrick Barnwall of Beymore. Neither the Civil Survey of 1654 to 1656 nor the terrier accompanying the Down Survey map specifically mentions the building, which is curious given its apparent scale.

The ruins were conserved at some point, an effort almost certainly motivated by aesthetics rather than archaeology: the building sits within clear sightlines of Headford House, approximately 1.3 kilometres to the north across the river, and a managed ruin in a field makes a more agreeable prospect than a collapsed one. It stands at the centre of a field system that is probably contemporary with the structure itself, which gives the whole arrangement a coherence that its current fragmented state somewhat disguises.