The site, marked on old Ordnance Survey maps from the third edition, occupies a modest space atop this natural outcrop; roughly 30 metres from north to south and 17 metres east to west, forming an irregular rectangle. A modern stone wall now encloses the summit, replacing whatever ancient fortifications once stood here.

The interior of the fort tells a story of centuries of weathering and neglect. The ground slopes noticeably downward from south to north, with exposed bedrock breaking through the surface at various points, creating an uneven, rough terrain that would have presented challenges even to its original inhabitants. This ringfort, whose classification remains uncertain amongst archaeologists, sits within a landscape characterised by rolling ridges of rock interspersed with patches of good grazing land; a typical setting for such defensive structures in medieval Ireland.

While the physical remnants of An Caiseal may be sparse, its placement speaks to the strategic thinking of those who built it. These elevated positions offered clear views across the surrounding countryside, essential for spotting approaching visitors or threats, whilst the natural rock formations provided ready building materials and additional defensive advantages. Today, it stands as one of many such sites documented in the Archaeological Survey of County Donegal, a testament to the dense network of fortified settlements that once dotted this northwestern corner of Ireland.