It is the kind of detail that passes unnoticed at first glance, yet it speaks to the practical intelligence of the people who constructed it, probably somewhere in the early medieval period, when such enclosures were a common feature of the Irish farming landscape.

A rath, as this type of earthwork is sometimes called, is a roughly circular or oval enclosure defined by a raised bank of earth, typically with a ditch outside it. This one at Roughgrove in County Cork is oval in plan, measuring around 31.5 metres north to south and 35.5 metres east to west, enclosed by an earthen bank standing approximately 1.5 metres high. To the east, the fosse, which is the external ditch dug to provide material for the bank, has largely silted up over the centuries. Thousands of similar enclosures survive across Ireland, most of them the remains of defended farmsteads belonging to ordinary farming families rather than warriors or kings, though the distinction was not always clear in early medieval Irish society.