There is nothing to see on the surface, no earthwork, no depression, no sign that anything lies below. The site is a souterrain, an underground stone-lined passage or chamber built, most likely, during the early medieval period. Souterrains are found across Ireland and were associated with nearby settlements, used variously for storage, shelter, or refuge, though the precise function of any individual example is rarely certain.

The Creevagh souterrain came to light during a 1987 survey of the wider Clonmacnoise area, recorded by McDonald. That survey was part of the broader effort to document archaeological features in the hinterland of Clonmacnoise, the celebrated monastic site on the River Shannon that served as a major ecclesiastical and scholarly centre from the sixth century onwards. Whether this souterrain had any direct connection to activity at Clonmacnoise, or simply reflects the general density of early medieval settlement in the region, is not recorded. It entered the published Archaeological Inventory of County Offaly in 1997, noted plainly as not visible at ground level, a description that doubles as both a practical observation and an accidental summary of the site's entire character.

For anyone curious enough to seek it out, the honest answer is that there is very little to observe on the ground. Its value lies less in what can be seen and more in what the record suggests: that the fields of Creevagh carry, somewhere underfoot, a structure built and used by people whose settlement has otherwise left no obvious trace above the surface.