Historical records paint a picture of what was once here; in 1840, observers noted the castle ruins measured about 60 feet square, surrounded by a substantial court wall spanning 130 feet by 160 feet. Even then, the walls were described as “completely defaced”, with the ruins deemed insignificant. By the 1940s, when archaeologist O’Kelly visited the site, he found only that pile of boulders remaining, though he noted O’Donovan’s earlier measurements of the structure.

The castle’s documentary history is equally sparse. Thomas Westropp, writing in the early 1900s, placed the site near Cashelmongan and noted that in 1655 the land was held by J. Lysaght, before being granted to Lord Kingston in 1667. Curiously, no castle appears on the Down Survey maps from 1654-7, nor is it mentioned in the Civil Survey of Limerick from around the same period, suggesting the structure may have already fallen into ruin or been of limited significance by the mid-17th century.

Today, even those boulder remnants have vanished from view. Digital aerial photographs show no visible traces of the castle site, leaving only the historical records compiled by antiquarians and archaeologists to tell its story. The disappearance of Garryellen Castle serves as a reminder of how quickly even substantial stone structures can fade from the landscape, particularly when they fall out of use and maintenance in turbulent times.