The main mill at An Aird Thiar was a horizontal mill, a design common in Ireland for centuries in which water was directed onto a wheel lying flat beneath the millstone rather than turning vertically as in the more familiar image. It was still working until around 1900, but at some point after that it was demolished, its stone repurposed for a nearby bridge. The building is gone, then, though contemporary descriptions of how it looked and functioned have survived.

The place name itself preserves the memory: Loch an Mhuilinn translates roughly as the lake of the mill. A short distance upstream, a second, smaller mill also once operated. Known as An Muileann Beag, the little mill, it too has vanished as a working structure, though its foundations remain visible at a bend in the river. The two mills together suggest a stretch of water that was once genuinely industrious, channelling the flow from the lough to grind grain for the surrounding community. The scholars A. T. Lucas and Tim Robinson both noted the site in 1953 and 1985 respectively, Robinson's attention to the landscape of Connemara in particular lending the record a degree of geographical precision.

The surviving foundations of An Muileann Beag by the river bend are the most tangible remnant of this small milling complex. The bridge built from the first mill's stone is, in its own way, a kind of continuation, the material of one structure absorbed quietly into another.