What makes this one at Clonmannan quietly interesting is how clearly it speaks to the practical ambitions behind the grand houses it served. A lime kiln was a working furnace used to burn limestone at high temperatures, producing quicklime for mortar, plaster, and agricultural use. This one, standing on level ground near the north-western edge of the old Clonmannan demesne, was built specifically to support the construction of the houses on the estate, and it survives close enough to Wicklow Bay to remind you how coastal estates once organised their resources.

The structure is rectangular in plan, measuring roughly 5.1 metres along its north-west to south-east axis and 4.1 metres across. It dates to the early to mid nineteenth century at the latest, though it may be older, and was almost certainly associated with one or both of the Clonmannan Houses situated to the south, the original house lying around 53 metres away and a later replacement approximately 170 metres further still. The construction itself is a study in materials working together: rubble stone masonry forms the bulk of the structure, but the upper section of the north-western elevation shifts to red brick, and a segmental-headed arch in the same red brick frames the oven aperture at ground level. That aperture slopes inward towards the central firing chamber, a detail that concentrates both heat and attention on the functional heart of the whole structure.