The site at Caherbeg is a rath, the most common type of ringfort found across Ireland, typically built during the early medieval period as a farmstead enclosed by one or more circular banks and ditches. What makes this example worth pausing over is the layering of its defences and the traces of daily life that survive within.

The enclosure measures roughly 40 metres north to south and 43.5 metres east to west, making it a reasonably substantial example of the type. Two concentric earth and stone banks surround the interior, separated by a fosse, which is simply a ditch dug to heighten the defensive effect of the bank on its outer side. The inner bank still stands to around 1.6 metres and the outer to about 1.2 metres, with both retaining stone facing in places, a detail that suggests some care was taken in their original construction. A shallow outer fosse, surviving to only about 0.3 metres in depth, runs along the north-west and north-east sides. The main entrance was to the east, reached by a causeway across the fosse, which would have been the formal, controlled point of access into the enclosure. There are also breaks in the outer bank to the west and south-east, though whether these are original features or later disturbances is not certain. Across the interior, cultivation ridges run on an east-west axis, the faint corrugations of old tillage preserved in the turf. Perhaps most intriguing is a possible souterrain in the western half of the interior. A souterrain is an underground stone-lined passage or chamber, built beneath ringforts for storage, refuge, or both, and their presence is a reliable sign that people actually lived and worked within the enclosure rather than simply using it for livestock.