The only evidence we have of its existence comes from historical records and the observations of antiquarians who documented what little remained before it disappeared entirely. The castle gets a brief mention in a 1341 extent, a type of medieval survey that recorded lands and properties, suggesting it was already an established structure by the 14th century.

By 1840, when the historian Westropp visited the site, only the foundations of Galbally Castle remained visible, and even these were so badly deteriorated that he couldn't take proper measurements. The Ordnance Survey maps of Ireland, created in the 19th century as part of a comprehensive mapping project, still marked the castle's location, preserving its place in the cartographic record even as the physical structure crumbled away.

Today, visitors to Galbally will find no trace of the castle that once stood here; the site has been completely erased by time and development. This disappearance is not uncommon for smaller Irish castles, particularly those that fell out of use early and weren't maintained or repurposed for later buildings. What we know about Galbally Castle comes entirely from these fragmentary historical mentions, compiled by researchers like Caimin O'Brien as part of the Urban Survey of Limerick, reminding us how much of Ireland's medieval heritage exists only in documents and memory.