The tower forms part of a complex that once dominated this small parish in County Meath, appearing on the Down Survey maps of 1656-8 alongside a gabled house. Historical records from the Civil Survey reveal that by the mid-17th century, Sir Richard Barnwall of Crickstown and Walter Stanly controlled the entire 472-acre parish of Fennor, which encompassed the neighbouring townlands of Johnstown and Bodnamrock; their holdings included both the castle and a fishing weir on the river below.

The castle tower itself reveals several phases of construction and adaptation over the centuries. Built separately from the adjoining house, as evidenced by the lack of bonding between the structures, the tower features characteristic defensive elements including a base batter and narrow slit windows in its north wall. The ground floor retains its original stone vaulting, whilst the upper levels show signs of later modification with larger windows that would have made the space more habitable. A gable was eventually added over the north wall, and in a practical twist typical of Irish tower houses, the entire structure was repurposed as a staircase when connected to the adjacent dwelling.

Just 40 metres north of the castle stands the parish church of Fennor, creating a small but significant medieval settlement cluster. This proximity between ecclesiastical and defensive structures was common in medieval Ireland, where local lords often built their strongholds near churches to reinforce their authority over both the spiritual and temporal affairs of their territories. Today, these ruins offer a glimpse into the layered history of rural Meath, from its medieval fortifications through to the detailed cartographic surveys of the Cromwellian period.