It exists, for now, as a cropmark, one of those ghostly outlines that appear in aerial photographs when dry summers stress the vegetation growing over buried ditches, making ancient earthworks briefly legible from above. The circular form, somewhere between forty and forty-five metres in diameter, is defined by a single fosse, a cut ditch running from the south-east, around the west, to the north-east, tracing most of a circle in the soil beneath the fields.

What makes the site particularly interesting is how it sits in relation to its neighbour. Immediately to the east lies a bivallate rath, a type of enclosed farmstead common in early medieval Ireland, distinguished from a simpler rath by having two concentric earthen banks and ditches rather than one. The enclosure at Lewistown appears to be physically attached to the outer fosse of this rath, suggesting the two features are connected, perhaps built together, perhaps one added to the other over time. Whether the circular enclosure served as an annexe for livestock, a defined working area, or something else entirely is not known. Both features are visible on aerial photographs taken in July 2000, confirming that the cropmarks remain legible under the right conditions.