The juxtaposition is not unusual in rural Ireland, but it still gives pause. The monument in question is a cashel, a type of ringfort built from stone rather than earthen banks, and the one at Knockash has been carrying the indignity of modern infrastructure quietly inside its walls.

The cashel was identified through aerial reconnaissance in June 1986, when its outline became legible from above despite being largely reduced to a low, grass-covered stony bank. It is subcircular in plan, measuring roughly 25.5 metres north to south and 21.6 metres east to west. The bank survives best on the eastern side, where it still reaches an external height of 0.65 metres and a width of around 3 metres, though internally it barely clears 0.3 metres. The site sits approximately 100 metres east of a hillfort, suggesting this stretch of landscape was in use across different periods and perhaps served layered purposes over time. Attached to the southern edge of the cashel is what appears to be a small annexe or house site, almost square in shape at roughly 6 by 5 metres. It is composed partly of natural clints, the flat slabs of exposed limestone pavement characteristic of Galway's karst terrain, along with small loose stones, and it is in very poor condition.

What a visitor would find today is a site that requires some imagination to read. The bank is visible all the way round if you know to look for it, and the eastern arc gives the clearest sense of what the enclosure once was. The concrete shed and mast in the interior are the most immediately obvious features, which is perhaps the strangest thing about visiting an early medieval monument that has, in effect, been pressed into continued service.