The earthwork at Benisonlodge is a rath, a type of ringfort consisting of a roughly circular raised enclosure defined by an earthen bank and a fosse, or external ditch, that would once have enclosed a family's dwelling, their animals, and their stores. Thousands of these were built across Ireland between roughly the early centuries AD and the twelfth century, and they remain one of the most common archaeological features in the Irish landscape. This one, however, is well advanced in the process of being absorbed back into the farmland around it.

By 1837, when the Ordnance Survey recorded it on their six-inch map, the enclosure was already being carved up by post-1700 field boundaries cutting across its northern, south-south-east, and south-south-west edges. By the time the revised twenty-five-inch map was produced in 1911, the shape had shifted in how it appeared on paper, rendered more rectangular as field boundaries at the south and west continued to redefine it on the ground. What survives today is a sub-circular raised area approximately thirty metres across on its north-south axis and nineteen metres east to west, with a poorly preserved bank and a shallow fosse still legible from the north, east, and south-east. A probable entrance gap, about 1.7 metres wide, is visible at the south-east. Across the interior, running east to west, are faint traces of cultivation ridges, suggesting the enclosed space was turned over to tillage at some point after the ringfort fell out of use. The interior also slopes gently from south down to north, a detail that gives the whole structure a quietly tilted, time-worn character. A line of trees marks its presence on aerial photography, which is often how such sites first draw modern attention when everything else has been reduced to a slight rise in a field.