Though no stone walls remain today, this location once held a fortified structure that appeared on early Ordnance Survey maps from 1837, where it was marked as a square enclosure measuring roughly 23 metres on each side. By the time the maps were revised in 1913, the site had already been reduced to an oblong mound, testament to the castle’s destruction sometime in the intervening decades.

Historical records from the Down Survey suggest that no castle existed here during the 1640s, when the lands belonged to Alexander Hope. This indicates the structure was likely built sometime after the mid-17th century, though its exact construction date remains unknown. What visitors see today is essentially a long, rectangular mound of earth and stone, approximately 16 metres in length and rising to about 4 metres at its highest point. This grass-covered heap of rubble, running northwest to southeast, represents all that remains of the levelled castle; its stones apparently gathered and piled along what may have been a ruined wall.

The mound itself tells an interesting story of deliberate demolition rather than natural decay. Its steep sides and relatively flat, narrow top suggest the castle’s stones were methodically stacked after the building was pulled down. Small limestone rubble is particularly abundant on the western side, where the mound curves slightly inward, with another pile of rubble sitting just to the northwest. The surrounding fields still show traces of old cultivation ridges, evidence that this defensive site eventually gave way to agricultural use, leaving only this earthen monument to mark where Glascarn Castle once stood.