The pairing of two very different kinds of past is quietly odd: a rath is a circular earthen enclosure dating from the early medieval period, typically associated with a farmstead or settlement of that era, and here a much later industrial structure has been built directly into its bank, the one era borrowing from the other without ceremony.

The kiln itself is a solid piece of vernacular construction. Its front wall, facing south, runs to about five metres wide and stands roughly two and a half metres high, built of random rubble, meaning irregular uncut stone laid without formal coursework. The eastern side matches this approach. A lintelled recess, that is, an opening spanned by a flat horizontal stone, sits off-centre to the left of the front face. Lime kilns of this type were once commonplace across rural Ireland, used to burn limestone at high temperatures to produce quicklime, which farmers spread on acidic fields to improve soil fertility. The funnel opening at the top, where fuel and limestone would have been fed in, measures around 1.8 metres in diameter, though it is now blocked. Collapsed stonework from the structure has been gathered and stacked neatly against the western side, suggesting the kiln saw some tidying at a later point, even as the funnel was left plugged with whatever machinery came to hand.

What makes the Coolbane kiln worth a second thought is less the kiln itself than its situation. Building into an existing earthen bank was practical, providing insulation and structural support, but doing so against a rath meant disturbing, or at least making use of, a feature that by the post-medieval period was already centuries old. The farm machinery blocking the funnel adds a further layer: three distinct periods of agricultural life, the early medieval, the lime-burning era, and the age of mechanised farming, compressed into a single unremarkable-looking mound in a Kerry field.