The site at Garnagowlan, roughly twenty-three metres in diameter, is the kind of monument that exists more on paper than in the landscape, its outline preserved in cartographic memory long after the ground itself was put to other uses.

The enclosure was first recorded on the Ordnance Survey six-inch map of 1838, one of the earliest systematic surveys of the Irish countryside, which captured earthworks, field boundaries, and features that were already beginning to erode or be built over. On that map the circular feature is shown partially cut by a road to its northwest, suggesting it had already suffered some disturbance by the early nineteenth century. A circular enclosure of this kind would typically be understood as a rath or ringfort, a type of enclosed farmstead common in early medieval Ireland, defined by one or more earthen banks and ditches and used for settlement and livestock management. When the site was inspected in 1990, however, what remained was not a grassy bank in a field but a car park serving Woodenbridge Golf Club, the enclosure apparently lying directly beneath it.