It is a substantial structure, nearly seven and a half metres tall at the front and six metres wide, pressing its back against the living rock as though the quarry itself was always part of the design. That integration is exactly the point: the rockface served as a ready-made rear wall, and the quarried stone provided the raw material to be burned.

A lime kiln is essentially a furnace built to convert limestone into quicklime, which was used across rural Ireland to improve acidic soils and as a binding agent in mortar. The Ballintubbrid example follows a familiar form but retains enough original fabric to be worth attention. The south-east-facing front presents an arched recess, roughly two and a half metres wide and two metres deep, lintelled at the rear, through which the burned lime would have been extracted once firing was complete. That original stone arch has been partially filled in at the top and is now reinforced by a lower brick arch, a later intervention that tells its own story of continued use and quiet repair rather than abandonment. Behind the kiln, a low enclosing wall with a narrow opening in its east face and a loading ramp on the west side would have allowed workers to bring limestone up and tip it into the funnel from above. That internal funnel is stone-lined and beaker-shaped in cross-section, widening toward the top to receive the stone and narrowing toward the fire pot below, a form well suited to the controlled draw of air that sustained the burn.