The tree line follows the outer edge of an early medieval ringfort, a type of enclosed settlement, known here as a rath, that was built by farming families across Ireland roughly between the fifth and twelfth centuries. Thousands survive in various states across the country, but many have been ploughed away or quietly absorbed into field boundaries. This one, on a south-west facing slope in Cooga Upper, has held its shape.

The site appears on the first edition Ordnance Survey six-inch map of 1840, where it is recorded as a raised, oval-shaped area enclosed by a wide berm, a broad earthen bank that forms the perimeter of the enclosure. The overall dimensions, as recorded in the survey notes compiled by Alison McQueen and Vera Rahilly, run to approximately 67 metres on the north-east to south-west axis and 65 metres on the north-west to south-east axis, making it a substantial example of the type. The fact that it was already mapped in detail in 1840 suggests it was prominent enough in the landscape to be recognised as a distinct feature, and aerial imagery from Digital Globe taken between 2011 and 2013, and again from Google Earth in November 2018, confirms that the enclosure remains clearly legible from the air, outlined by that characteristic ring of trees.

The site sits in working pasture, so access is not guaranteed and any visit would require the landowner's permission. Because the monument is on a gentle south-west facing slope, the earthworks are likely to show most clearly in low winter or early spring light, when the grass is short and the angle of the sun throws any surviving banks into relief. The tree line itself, visible on satellite imagery, is the most obvious landmark to orient yourself by. Close up, a visitor should look for changes in ground level around the inner edge of the trees, where the remains of the original bank may still be legible beneath the turf.