Historical records paint a picture of gradual decline; by the early 20th century, antiquarian Thomas Westropp noted that the castle’s south wall had already fallen. Local schoolchildren collecting folklore in 1939 described finding only small portions of walls still standing, though they estimated the original structure measured roughly 24 feet by 22 feet wide, suggesting it had been a formidable defensive building in its day.

The castle’s history becomes somewhat murky when examining land records. The 1659 Civil Survey of Limerick mentions a ruinous castle and mill seat in the neighbouring townland of Thomastown, which lies immediately east of Mountblakeney. Some historians believe these may actually refer to the same structure, as townland boundaries have shifted over the centuries and castles were often associated with multiple place names. The survey’s description of the castle as already ruinous in 1659 suggests it had been abandoned or destroyed during the tumultuous period of the Cromwellian conquest.

Today, nothing visible remains of Mountblakeney Castle above ground. Modern aerial photography and satellite imagery show no trace of the walls that local children could still see in the 1930s, indicating the final stones have either been removed for building materials or have sunk beneath centuries of accumulated earth. The site serves as a reminder of how quickly even substantial stone structures can vanish from the landscape, leaving only documentary fragments and folk memory to mark where they once stood.