It is not. What the trees are following is the outline of a rath, a type of ringfort that served as a farmstead enclosure during early medieval Ireland, typically defined by one or more earthen banks and ditches thrown up to protect a household, its livestock, and its stores.

The monument at Knockuregare was already old enough to be unremarkable by the time the Ordnance Survey mapped it in 1840, where it appears on the six-inch edition as a circular area enclosed by a bank. The more detailed 25-inch edition of 1897 adds resolution to the picture, showing a raised circular platform of approximately 22 metres in diameter, defined by a scarp and an external fosse, that is, a ditch, running from the south-west around through the west to the north-west. A related enclosure, recorded separately under the reference LI030-195----, sits some 406 metres to the north-east, just across the townland boundary with Ballingayrour, suggesting that this part of Limerick held at least a modest cluster of early settlement activity. Orthophotography taken between 2005 and 2012 shows the tree-lined bank still clearly readable from multiple directions, and a Google Earth image from June 2018 picks out traces of the external fosse along the southern and western arc.

The site sits in pasture, roughly 61 metres west of the Ballingayrour townland boundary. Because it lies in a working agricultural field, access is not guaranteed without the landowner's permission, and the ground underfoot is likely to be soft for much of the year. The bank and its encircling trees are the primary thing to observe; look also along the south-western and western margins for any low-lying depression that might represent the surviving fosse. Aerial and satellite imagery, freely available through the Ordnance Survey Ireland portal and Google Earth, can help orient a visit and reveal the circular geometry that is less immediately obvious at ground level.