These stone-built structures, typically circular or horseshoe-shaped chambers set into a hillside or bank, were used to burn limestone at high temperatures, producing quicklime that could be spread across acidic soils to improve agricultural yields. For centuries they were as essential to a working farm as any outbuilding, and yet they rarely attract the attention given to ringforts or churches, precisely because they were so ordinary.

Lime kilns of this type were built and used across Ireland from at least the seventeenth century through to the early twentieth, when cheaper imported lime and later artificial fertilisers made them redundant. A farmer would pack the kiln with alternating layers of limestone and fuel, usually coal or wood, and keep it burning for several days. The resulting powder was slaked with water and carted out to the fields. What remains at sites like Rusheen is almost always the stone shell of the burning chamber, its draw arch still visible at the base, sometimes intact and sometimes partially collapsed, sitting in a hedgerow or at the edge of a field as though forgotten mid-task.