Built into a hillside on the demesne lands of Killua Castle in County Westmeath around 1800, this rubble limestone icehouse was a working piece of cold-chain infrastructure, the kind of structure that made syllabubs and chilled wine possible in a pre-industrial Irish summer. An icehouse of this type is essentially an insulated underground chamber, often dug into a slope to take advantage of the earth's natural temperature, where ice harvested in winter could survive well into the warmer months. This one, now partially collapsed and standing in open grassland where woodland once grew, consists of two entrance chambers leading down into the hillside at a slant.

What makes the place unexpectedly vivid is a piece of folklore collected from a pupil named Sean McGrath at Clonmellon School, part of the Irish Folklore Commission's Schools' Collection of the 1930s. McGrath recalled the structure in plain, practical terms: it sat on the left side of the path going up to Killua churchyard, just beside what he called Plunket's grand gates, and it ran deep and at an angle into the ground. More striking still is what he remembered his father doing: cutting ice from Killua Lake, located about 80 metres to the north of the icehouse, and carrying it to the structure to make ice-cream. The ornamental lake, the country house, the icehouse, and the labour of harvesting winter ice from the water all formed part of a single demesne economy, one that connected the pleasures of the castle table to a man working on a frozen lake with cutting tools.

The demesne also contains the ruins of a medieval church and graveyard roughly 160 metres to the north-east, giving the broader landscape a compressed historical range that moves from early Christian settlement through to the ambitions of Georgian estate management. The icehouse itself is now disused, its chambers open to the sky in places, sitting quietly in a field that no longer remembers the woodland that once surrounded it.