A bawn, in Irish fortified architecture, was the walled enclosure attached to a tower house, used to protect livestock and provide a defensive outer layer. This one surrounds the remains of Muckinish Castle, and the little rectangular structure tucked into its corner measures only 7.5 metres east to west and 3.8 metres across, with walls a modest 0.6 metres thick. Its eastern gable still stands to a height of 3.5 metres, steeply pitched, and pierced by a single narrow slit window. The western gable has not survived, and the interior is now filled with rubble.

The building is tentatively dated to the 17th century, though the date remains uncertain, which is itself part of what makes it worth attention. It appears on both the 1842 and 1915 editions of the Ordnance Survey six-inch maps, suggesting it was at least a recognised feature of the landscape well into the modern period. Its setting adds a layer of quiet interest: Pouldoody Bay offers two small inlets to the east and west-north-west that appear to function as natural landing points, tidal in character, with higher pastureland rising gently to the south. Whether the building served those who worked the land, those who used the water, or those who occupied the castle complex is not recorded. It sits at a junction of several older purposes, a coastal approach, a defended enclosure, and an agricultural hinterland, without declaring its own role in any of them.