It measures roughly fifty metres north to south and forty-four metres east to west, with the remains of an earthen bank still standing to about 0.7 metres in places, accompanied on its outer edge by a fosse, a shallow external ditch, dropping some 0.4 metres below the surrounding ground level. The bank and fosse survive along the south-east to north-north-west arc, but have been levelled on the north-east to south-east side, leaving only a partial outline where a complete boundary once stood.

Enclosures of this kind, broadly described as ringforts, were the standard form of rural settlement in early medieval Ireland, used as farmsteads and defended homesteads by families of varying social rank. They are typically dated to the period between roughly 500 and 1200 AD, though individual examples can be difficult to date without excavation. The earthen variety, known as a rath, relies on a raised bank rather than stone walling to define the enclosed space, and the accompanying fosse provided both the material for that bank and an additional obstacle. The site at Lisnamurragh is recorded in D. Lavelle's 1994 archaeological survey of the Ballinrobe district, which catalogued monuments around the shores of Lough Mask and Lough Carra. What survives today is a partial impression in the landscape, the levelled north-eastern section a reminder of how readily agricultural land use can reduce these earthworks over centuries.