These defensive earthworks, which likely date from the 13th to 14th centuries, consist of a raised rectangular platform surrounded by a water-filled ditch or moat. The site would have originally supported a timber-framed dwelling, probably belonging to an Anglo-Norman settler or a Gaelicised Norman family who adopted this particular style of fortified homestead during the medieval period.

The moat itself, though now partly silted up, would have served multiple purposes; it provided defence against raids, acted as a status symbol for its inhabitants, and offered practical benefits such as drainage and a ready source of water. Unlike the stone castles built by wealthier Norman lords, moated sites represented a more modest yet still formidable type of fortification that spread across Ireland during the medieval colonisation period. The earthwork platform, typically measuring between 30 to 50 metres square, would have been accessed by a wooden bridge or causeway, traces of which have long since disappeared.

Today, the Balla moated site stands as one of approximately 230 such monuments identified across Ireland, with the majority concentrated in the eastern and southern counties. Its survival in Mayo, where moated sites are less common, makes it particularly significant for understanding the extent of Anglo-Norman influence in the west of Ireland. The site remains largely undisturbed, its grassy banks and tree-lined moat offering visitors a tangible connection to the medieval landscape and the complex cultural exchanges that shaped Ireland during this transformative period.