A keyhole-shaped cut in the ground, roughly two metres across at its widest point, with a narrow flue channel angling gently down into it: this is not much to look at on paper, and by the time it was recorded it had long since been buried under agricultural topsoil on the eastern fringes of Kildare. Yet the kiln uncovered at Collinstown during roadworks near the Celbridge Interchange in 2001 turned out to have two distinct lives, one layered directly on top of the other, separated by nothing more than a sealed deposit of earth.

The site came to light between April and December 2001, during monitoring of topsoil-stripping for a road scheme approximately four kilometres long running from Celbridge to Leixlip. Eighteen potential archaeological features were identified along the route; this one, designated Site 18, was among the more structurally legible. A kiln of this type, sometimes called a corn-drying kiln, was a common agricultural feature across medieval and post-medieval Ireland, used to dry grain before milling or storage, typically by drawing heat through a flue into a bowl-shaped chamber. At Collinstown, the earlier phase survives only as a charcoal deposit at the base of the cut. The later phase was more substantial: a single course of roughly hewn stones lining the circumference of the bowl, with the largest stones placed deliberately at the neck of the flue, which faced north-west. A low wall to the north-west of the kiln, surviving as a single course for most of its length, may have served as a windbreak. The fill of the kiln's destruction layer contained burnt and unburnt animal bone, along with sherds of both medieval and post-medieval pottery. No dateable artefacts were found within the use phases themselves, which leaves the chronology frustratingly open. The medieval pottery points to activity in the area during the medieval period, possibly including the kiln's active life, while the post-medieval pottery in the destruction layer suggests it had fallen out of use and begun to collapse by sometime after the sixteenth century. The broader landscape here was heavily reshaped in the eighteenth century, centred on Castletown House, which makes earlier features harder to read in the present topography. The charcoal deposits were sampled for cereal remains and other environmental evidence, which may yet add detail to what the pottery alone cannot resolve.