The field above it looks ordinary enough, a roughly circular platform measuring about 32 metres north to south and 30 metres east to west, defined by an earthen bank that barely rises 20 centimetres above the surrounding ground. Easy to walk past without a second thought, which is precisely what makes it worth pausing over.

This is a rath, the most common type of early medieval settlement monument in Ireland. A rath was typically a farmstead enclosed by one or more earthen banks, used by a single family or small community, most likely between the sixth and tenth centuries. The low bank at Knockglass is all that survives above ground, worn down over centuries of agricultural use. More intriguing is the souterrain associated with it: a souterrain is a man-made underground stone-lined passage or chamber, usually dug beneath or beside a ringfort, and thought to have served as a place of refuge, cool storage, or both. The one at Knockglass is recorded but currently inaccessible, which means its interior dimensions, construction, and condition remain largely unknown to casual observers.