This four-storey stone tower featured a vault over its third floor and appeared in historical records as early as 1640, when it belonged to John Lee. The castle featured in the Down Survey of 1655-6, one of the most important cartographic undertakings in Irish history, which documented land ownership following the Cromwellian conquest of Ireland.

By 1778, Taylor and Skinner’s map marked the structure as a ruin, suggesting it had already fallen into disrepair by the late 18th century. When antiquarian John O’Donovan visited the site around 1840 as part of the Ordnance Survey of Ireland, he documented the castle’s architectural details, providing valuable insights into its original construction. His descriptions remain one of the few detailed accounts of the building’s physical appearance.

Today, not a trace of Castle Connagh remains above ground; only a single dressed quoin stone built into a nearby roadside bank hints at its former presence. Archaeological testing conducted in 2005 revealed that extensive quarrying had taken place at the site, likely explaining the castle’s complete disappearance. The stone from the castle was probably repurposed for local construction projects over the centuries, a common fate for abandoned fortifications throughout Ireland. This vanished stronghold now exists only in historical documents and maps, a reminder of the many lost castles that once dotted the Irish landscape.