Visible only from above, in satellite imagery taken between 2005 and 2012, the ghost of its fosse traces a near-perfect circle in the soil, roughly 23 metres in diameter, legible to those who know what they are looking for.

The enclosure was recorded on the first edition Ordnance Survey six-inch map of 1839, which captured Irish field monuments with a thoroughness that would not be matched again for generations. By the time a revised map was produced in 1948, the feature had been omitted, and the monument itself levelled, most likely through agricultural clearance in the intervening century. A fosse, in this context, is simply a ditch dug around an enclosure to define and defend its boundary; in Ireland such features typically surrounded early medieval settlements, ringforts, or enclosed farmsteads. The physical earthwork at Grovebeg is gone, but the fosse left a lasting impression in the subsoil that satellite sensors can still detect as a crop or soil mark, a faint stain of a different era.