When surveyed in 1847, investigators found the foundations of a building measuring 50 feet by 14 feet, with surviving walls that stood between one and five feet in height. The structure was oriented east to west, a common alignment for ecclesiastical and defensive buildings of the medieval period in Ireland.

Today, no visible trace of this castle remains above ground, making it one of many lost medieval sites scattered across the Donegal landscape. The complete disappearance of the structure over the past 175 years speaks to the vulnerability of Ireland’s built heritage, whether through stone robbing for local construction, agricultural clearance, or simple weathering and decay. The original function of the building remains uncertain; its dimensions suggest it could have been a small tower house, a fortified dwelling typical of the late medieval period, or perhaps an earlier defensive structure.

The site was documented as part of the comprehensive Archaeological Survey of County Donegal, compiled by Brian Lacey and his team in 1983. This survey represents one of the most thorough catalogues of Donegal’s archaeological heritage, recording everything from Mesolithic settlements to 17th-century structures. While the Ballymagrorty Irish castle may have vanished from the physical landscape, its inclusion in this survey ensures that future generations will know of its existence and approximate location, preserving at least the memory of this lost piece of Donegal’s medieval past.