Not a castle, not a church, not a tower house with a name attached to a dynasty, but simply a farm, described in a mid-seventeenth-century survey and then, for practical purposes, lost. Its precise location has never been established.

The reference comes from the Civil Survey of 1654 to 1656, one of the most ambitious attempts to document landholding in Ireland following the Cromwellian conquest. The survey, edited by R.C. Simington and published in 1945, records the "farme at Portrane" in passing, a phrase that tells us the place existed during the sixteenth or seventeenth century but offers little else in the way of particulars. The Civil Survey was itself part of a broader project to quantify confiscated and redistributed land across the country, and entries like this one, sparse and unanchored, were not unusual. A farm might be noted for the purposes of valuation without any obligation to fix its coordinates or describe its buildings in detail. What survives is a name, a general area, and a date range.

Portrane today is a coastal townland on the Fingal coast, perhaps best known for the large institutional complex built there in the early twentieth century. The earlier, agricultural landscape that would have framed this unnamed farm is considerably harder to read on the ground. For anyone interested in following up the reference, the Civil Survey volume covering County Dublin, edited by Simington, is the logical starting point, held in major research libraries. The site itself, unlocated as it is, cannot be visited in any direct sense, though the broader Portrane area retains a quiet, flat shoreline character that offers some feel for the kind of marginal, sea-edged farming country the survey entry implies. What the place actually looked like, who farmed it, and what became of it remain open questions.