The Civil Survey, that comprehensive 17th century record of Irish lands, referred to it simply as the 'old Castle', suggesting it was already in ruins by the 1650s. By 1847, when the antiquarian Fagan came to document the site, he could find no visible remains whatsoever; the castle had completely vanished from the landscape.

The disappearance of Bundrowes Castle isn't unusual for Ireland's medieval fortifications. Many such structures were built using local materials and, once abandoned, were often quarried by locals who saw ready dressed stone as too valuable to leave standing idle. Without maintenance, what stone remained would have been reclaimed by nature or buried beneath centuries of soil accumulation.

What little we know of Bundrowes Castle comes from historical documents rather than physical evidence. Its inclusion in the Civil Survey indicates it held some significance in the medieval or early modern period, likely serving as a stronghold for a local family or as part of the defensive network that once dotted the Donegal countryside. Today, the site serves as a reminder that Ireland's historical landscape contains countless invisible monuments; places where castles, churches, and settlements once stood but have since returned to earth, leaving only their names and brief mentions in old records.