This fortification consists of a polygonal bawn, a type of defensive wall that would have enclosed and protected a settlement or tower house. The roughly coursed rubble masonry walls still show evidence of musket loops, narrow openings through which defenders could fire upon attackers whilst remaining protected. Within the southern section of the bawn, foundation walls suggest two possible building sites, one of which may have been the castle itself that gave this townland its name.

What makes Castleroan particularly intriguing is its defensive layout. The bawn sits atop a north-facing slope surrounded by a wide, flat berm; essentially a level strip of ground that would have made approaching the walls more difficult for attackers. Beyond this lies a deep fosse, or defensive ditch, with a causewayed stone entrance to the east. These outer defences have been partially disrupted by a modern road on the northern side, but enough remains to understand the site’s impressive defensive strategy. The polygonal shape of the bawn is relatively rare in Ireland, with a similar example found at Ballinlough Castle in the same county.

Historical records add another layer to Castleroan’s significance. The Down Survey maps from 1654-7 mark it as ‘Caiseal Roan’, confirming its importance in the mid-17th century landscape. Archaeological evidence suggests this may have been a medieval bawn with a tower house, possibly built atop even earlier earthworks. Whilst the tower house itself has long since vanished, the surviving bawn walls and defensive earthworks offer a fascinating glimpse into how medieval communities fortified themselves in the Irish midlands.