A housing development south of Station Road in Portmarnock, Co. Dublin, covers the ground completely, and the monument recorded here was fully removed by archaeological excavation before the first foundations were laid. That erasure is, in its own way, part of the story: what vanished was a corn-drying kiln, a type of small sub-surface furnace used throughout early medieval Ireland to dry or parch harvested grain before milling or storage, and it had been waiting underground for somewhere between nine hundred and eleven hundred years before anyone knew it was there.

The kiln, designated C261 in the excavation records, came to light during two phases of work carried out between May 2016 and April 2017 under licence 16E0613, directed by Gill McLoughlin of Courtney Deery Heritage Consultancy Ltd. In total it measured 3.8 metres long by 1 metre wide and just 0.3 metres deep, aligned north to south, with a bowl at the northern end and a stoke hole to the south. The lowest fill was a dense, charcoal-rich black silty clay still containing cereal grain, and a radiocarbon date on charred wheat from this layer returned a calibrated range of AD 883 to 1011, placing the kiln's last use towards the end of the early medieval period. Intriguingly, the grain assemblage was dominated by wheat rather than barley; elsewhere on the same site a second kiln, C119, dated to the 5th or 6th century and showed a barley-dominant crop mix, consistent with current research suggesting barley declined in favour of other cereals across Irish sites after around AD 700. The kiln was not alone. It sat within a large, slightly elliptical ditched enclosure roughly 77 metres by 70 metres in external diameter, which also contained evidence of metalworking, a single adult male burial, and fragments of E ware, a type of imported pottery from western Gaul associated with high-status early medieval sites in Ireland and Britain. The fills of the kiln itself yielded animal bone, seashell, and slag, deposited after the structure went cold for the last time, possibly after an accidental fire.

Because the site has been entirely built over, there is no physical trace left to visit, and no above-ground feature marks the spot. The excavation reports by McLoughlin, submitted to the National Monuments Service on behalf of Sherman Oaks Ltd., remain unpublished in the conventional sense but are lodged with the relevant authorities. The adjacent Portmarnock mound, recorded as DU015-014, still stands east of the railway line and offers at least a topographical hint of the wider early medieval landscape that once existed here, even if the enclosure and its kilns are now preserved only in the archive.