The relationship between the two structures is not accidental or coincidental; the tower house occupies the cashel's south-eastern quadrant as though the older ring-wall were always intended to serve it. It is an unusual arrangement, and one that points to centuries of layered occupation on a single gentle rise above good Clare pasture.

A cashel is a stone-walled ringfort, the drystone equivalent of the more common earthen rath, and Cahercloggaun is a well-preserved example. The enclosure is subcircular, roughly 33 metres north to south and 31 metres east to west, with a wall between 3.2 and 3.5 metres thick. The outer face reaches over three metres in height on the western side and is built on a low plinth with a slight base-batter, meaning the wall leans fractionally inward from the ground up, a technique that adds stability to dry-laid masonry. Cunningham, writing in 1980, observed that the south-western section is particularly massive, with huge regular blocks producing upright joints at intervals of a few feet. The inner face is lower and most legible between the south and west. Several low interconnecting banks cross the interior, though their purpose is not fully resolved. The site gave its name to both the castle and the townland, and by 1839, when Ordnance Survey officers were compiling their letters on Clare, locals already described it simply as an ancient caher. It appears hachured on the 1842 six-inch map and is named Cahercloggaun on the 1915 edition. Fitzpatrick, writing in 2009, identified it as one of only three such stone enclosures in the region that can be directly associated with a late medieval tower house, a pairing that suggests the cashel carried social or territorial significance well beyond its original period of construction.