This one, sitting on a high limestone bluff in Coole Demesne, County Galway, achieves the same effect entirely inland. To the east lies Coole Lough; to the west, a turlough, one of those seasonally flooding lakes characteristic of the Burren and its fringes, with Doo Lough visible beyond it. The bluff's eastern and western edges are sheer precipice, which left only the southern approach requiring a man-made barrier. That barrier still exists, after a fashion, as a collapsed but substantial limestone wall running 29 metres across the southern end of the bluff.

The wall is built from large blocks of rubble limestone and presents differently depending on which side you examine it from. Externally it has partially collapsed; internally the collapse is more pronounced, held in place by a natural ledge before it drops away into a deep hollow below. That hollow, which occupies much of the area enclosed by the wall to the south, appears to be geological rather than quarried or dug, an accident of the karst landscape that the fort's builders chose to exploit. Several mature ash trees have taken root within it, their height giving some sense of how far the ground falls away. The best-preserved section of the wall survives at its western end, where the base measures over five and a half metres wide and the internal face still stands to 2.3 metres; this section may have been rebuilt at some point. The monument is thought to be the likely origin of the townland name Doonowen itself, suggesting it was a presence significant enough to shape the local landscape in memory long after it fell into ruin.