Inside it sits a windmill. The pairing is quietly puzzling, the kind of cartographic detail that rewards close reading of old maps, where the labelling choices of nineteenth-century surveyors sometimes preserve memories of earlier land use that have since been obscured at ground level.

The OS six-inch survey, carried out in the 1830s, was the first large-scale systematic mapping of the entire island, and its surveyors were generally careful about distinguishing earthwork types. The word "Fort" in this context most likely refers to a pre-existing circular earthen enclosure, the kind of ringfort or rath that was a common form of enclosed farmstead in early medieval Ireland, typically defined by one or more earthen banks and ditches. That a windmill was subsequently built within or immediately beside such an enclosure is not entirely surprising; elevated, well-drained ground within a pre-existing circular boundary offered a practical site for a mill tower, and earlier features were frequently reused without ceremony. The notes compiled by Geraldine Stout, and later updated by Christine Baker, also record that there has been some landscaping around the base of the windmill, which may have altered the legibility of whatever earthwork survives.

Balrothery village is small and easily missed on the road between Balbriggan and Lusk. The enclosure and windmill sit within this settled landscape, and the surviving remains are modest rather than dramatic. Anyone visiting would do well to consult a copy of the 1837 OS six-inch map beforehand, available through the OSi historical map viewer, to understand what the surveyors recorded and to compare it with what is visible today. The landscaping noted in the records means the ground surface near the mill base may not clearly show the original earthwork profile, so an eye for subtle changes in ground level, slight rises or curves in the surrounding terrain, is more useful here than looking for obvious banks or ditches.