This unclassified cairn forms a nearly circular mound measuring 6.8 metres from north to south and rising 1.8 metres above the surrounding grassland. The structure's builders carefully arranged stones to create the mound, then encircled it with a kerb of larger stones; a common feature in prehistoric Irish monuments that helped define the cairn's boundaries and prevent the smaller stones from tumbling outward.

The cairn's prominent position atop the field suggests it held significance for the people who constructed it, though its exact purpose remains uncertain. Such monuments in Ireland typically date from the Neolithic to Bronze Age periods and served various functions, from marking burial sites to acting as territorial markers or ceremonial gathering places. The good grazing land surrounding it indicates the area has been valued for agriculture for generations, with modern farmers continuing to use the fields much as their ancestors might have done.

This particular cairn was documented as part of the Archaeological Survey of County Donegal, a comprehensive project completed in 1983 that catalogued field antiquities spanning from the Mesolithic period through to the 17th century. The survey, compiled by Brian Lacey and his team of archaeologists, provides crucial documentation of Donegal's rich archaeological heritage, ensuring sites like this Balleeghan Upper cairn are recorded for future study and preservation.