Built in 1377 by John O'Ferrall, Lord of Annaly, the castle stood just north of an earlier motte, creating a layered defensive complex that dominated the local landscape. Historical records paint a picture of its significance; the castle appears on the Down Survey map of 1655-6 in the townland of Lisnedila, marking its importance even centuries after its construction.

The castle's history was far from peaceful. In 1417, just forty years after it was built, the Annals of Connacht record that 'Lissardowlin Castle outside the bawn was burned', suggesting it suffered significant damage during the turbulent medieval period. Despite this early setback, the structure endured for centuries. By 1891, local historian Farrell noted that whilst only 'a few crumbling old walls at the foot of the moat' remained, the ruins still proved it had been 'a large and important erection'. Unfortunately, he also observed that most of the main structure, which had been reasonably well preserved until shortly before his visit, had been removed, likely for building materials.

Today, nothing of the castle remains visible at ground level. When historian G.H. Orpen surveyed the site in 1910, only the foundations could be traced. The complete disappearance of this once imposing fortress serves as a reminder of how quickly Ireland's built heritage can vanish when not actively protected. What was once a symbol of Anglo-Norman authority in medieval Longford has been reduced to an archaeological memory, its stones scattered and its exact location known only through historical documents and the enduring presence of its neighbouring motte.