The Gadgirth Old Ha' consists of a section of masonry held together with lime mortar set against the crag and another small section, circa 2.3m long and a maximum height of 1.5m high enclosing the area of circa 8.7m by 6m, apparently a corner of the building.

On the sides not protected by the river are the remnants of a fosse, moat or ditch and a drawbridge is said to have been located here.

[1] The historian John Smith in the 1890s visited the site and stated that only a short stretch of wall could be traced.

[3] Little is known of the history of this castle site, once held by the ancestors of the Chalmer, originally the De Camera family, which was replaced by their later 14th century Gadgirth Castle that stood around 500 metres or a quarter of a mile upstream on the same southern side of the River Ayr until demolished in 1808.

[3][6] Reginaldus de Camera (Chalmer) is recorded to have held the Barony of Gadgirth during the reign of William the Lion (1165-1214).