When surveyed in 1942, investigators found a pear-shaped artificial mound stretching 54 by 20 yards, rising eight feet at its southwestern end and sloping down to three feet at the northeast. The mound, composed of loose stone, sat on a low ridge beside a hollow that may once have held water; a strategic position typical of defensive structures from this period.

By the time the Offaly Historical and Archaeological Society documented the site in 1974, much had already changed. The society noted that the remains of the slight mound had been removed, marking another chapter in the castle’s slow dissolution. The 1942 survey had recorded mortared wall foundations with one visible corner atop the mound, though extensive digging had already obscured any readable floor plan. Investigators also discovered architectural fragments in a nearby cottage, including squared stones believed to have come from the castle and, most intriguingly, the side jamb of an unglazed window complete with bar holes, with 29 inches between transoms; classic features of late medieval Irish architecture.

Today, Garbally Castle exists more in historical records than physical presence, invisible at ground level and known primarily through these archaeological surveys. The site represents countless similar tower houses across Ireland that have gradually returned to the earth, their stones repurposed for local building projects, leaving behind only subtle traces in the landscape and fragments of masonry scattered through neighbouring structures.