What makes this particular site quietly troubling is not what it was, but what it has become: between a detailed field description made in 1980 and the present day, the earthwork appears to have been levelled almost entirely, leaving only the faintest ghost of a former enclosure visible on aerial photography.

Ringforts, known in Irish as raths, were enclosed farmsteads typically dating from the early medieval period, roughly the fifth to twelfth centuries. They usually consist of a raised circular or oval bank, sometimes with an external fosse (a ditch dug to provide material for the bank), enclosing a domestic area where a family and their livestock would have lived. The Slane Beg example was substantial. When examined in 1980, it measured approximately 51 metres east to west and 44 metres north to south, making it notably large by any standard, and its shape was roughly rectangular rather than the more typical circular form. The bank was still reasonably legible on the south-western to north-western arc, though elsewhere it had been worn to little more than a low scarp. A shallow fosse was traceable along part of the western side, its outer edge already cut into by old cultivation ridges. No entrance feature was identifiable. The site appeared on the Ordnance Survey six-inch map of 1837, annotated simply as "fort", but had already vanished from the revised twenty-five-inch edition of 1913, suggesting agricultural pressure on the monument was long-standing. Old ridge-and-furrow cultivation patterns within the interior pointed to the same gradual encroachment. By the time aerial imagery was examined in more recent years, the earthwork had been reduced to a trace detectable only from above, its physical presence in the landscape essentially gone.