That much is certain. What is not certain is where, precisely, it stood, and nothing of it survives above ground today. It exists now only as a notation on two seventeenth-century surveys, a structure recorded and then, in the centuries that followed, thoroughly lost.

The two sources that document it are among the most significant mapping exercises carried out in Ireland during the 1650s. The Down Survey, conducted between 1655 and 1656 under the direction of William Petty, was an extraordinarily ambitious project to map the forfeited lands of Ireland following the Cromwellian conquest, intended to facilitate the redistribution of territory to soldiers and creditors of the parliamentary cause. It shows a windmill near the seashore south of Clontarf castle. The Civil Survey, a companion document compiled between 1654 and 1656 through local testimony rather than direct measurement, independently mentions the same structure. The fact that both surveys note it suggests the windmill was a recognisable feature of the landscape at the time, likely used for milling grain, a common enough function for coastal windmills that could catch sea breezes where water-powered mills were impractical.

Because the exact location of the monument is unknown, there is no site to visit in any conventional sense. The shoreline south of Clontarf castle is today a suburban stretch of Dublin Bay, reshaped over centuries by land reclamation and development. A visitor curious about the area might walk the coast road near Clontarf and look out across the water, knowing that the landscape they see bears little resemblance to the one Petty's surveyors recorded. The windmill's absence from the modern streetscape is itself the point. Consulting digitised copies of the Down Survey maps, several of which are held by institutions including Trinity College Dublin and accessible online, gives a clearer sense of how the shoreline was understood in the mid-seventeenth century and where, roughly, such a structure might have stood.