A lime kiln, the kind of structure once common on large agricultural estates, was built here against a natural slope, and the scale of it is still legible: the south-facing front elevation runs nearly eight and a half metres wide and stands around six metres high. Lime kilns worked by loading limestone and fuel into a funnel from the top, burning the stone to produce quicklime for fertilising fields, making mortar, or treating timber and hides. The one at Castlelands still has its brick-lined funnel, roughly two metres in diameter, though the lower bricks have been shattered by the intense heat of past firings, and the base of the funnel is now infilled with debris. The rear of the structure has collapsed and the earthen core it once contained has spilled back into the cavity.

The kiln sits within the demesne associated with Mallow Castle, and its position in the woodland, built deliberately into the hillside, is typical of how these structures were sited: the slope allowed carts to approach at the upper level to feed the kiln from above, while the arched recess in the front elevation, roughly two metres high and nearly three metres wide, gave access at the base for raking out the finished lime. Around nine metres to the north of the kiln, a separate circular limestone structure, also built into the slope, survives to about two metres in height. With an internal diameter of around four and a half metres and an opening in its south wall, it may have served a related agricultural function, though its precise purpose is not recorded. Together, the two structures suggest a working complex rather than a single isolated feature, both of them constructed in the same random-rubble limestone style and integrated into the same sloping ground above the Blackwater.