The surviving corner tower, rising five metres high with walls over a metre thick, marks what was once part of the manor of Dunbrandon, granted to Walter Harrison in 1621–22 along with 1,500 acres of land. The castle’s strategic position made clever use of the river’s natural curve, which formed a loop roughly 80 metres long and 40 metres wide; though now filled with silt and only about a metre deep, this waterway once served as a natural defensive barrier, effectively creating a ready-made bawn or fortified courtyard without the need for additional walls.

The tower itself reveals glimpses of its former domestic arrangements through its architectural details. At ground level, a small light opening illuminates an internal recess measuring 1.3 metres wide and two metres high, likely used for storage or perhaps as a guard post. The first floor features a window that has attracted considerable local folklore; tradition holds that this very opening witnessed the dramatic elopement of Dervogilla with Diarmuid Mac Murrough, an event that would ultimately provide the English with their pretext for invading Ireland in the 12th century. Whether this particular tower could have stood in Tiernan O’Rourke’s time is doubtful, but the persistence of the legend speaks to how deeply these stories have embedded themselves in the landscape.

Today, visitors can still trace the curve of the old river channel, now wet but no longer flowing, and examine the putlog hole in the attached wall fragment that extends just 1.2 metres to the north; a small reminder of the wooden scaffolding that once supported the castle’s construction. The site offers a tangible connection to the plantation period, when English and Scottish settlers like Harrison received vast estates as part of James I’s colonisation scheme, forever altering the social and political fabric of counties like Leitrim.