This one, tucked into the slopes of Kilmashogue in the Dublin Mountains, does something different: it stops short. The enclosure is horseshoe-shaped, open to the east, as though whoever built it decided the hillside itself could do the rest of the work. That deliberate incompleteness is what makes it worth seeking out.

A cashel, to use the correct term, is a ringfort built from stone rather than earthen banks, and this example on Kilmashogue is a reasonably well-preserved specimen of the type. The enclosing wall is substantial, between two and two and a half metres wide, constructed from an inner and outer face of large stones packed around a rubble core, and still standing to roughly ninety centimetres in height. The internal diameter measures twenty-four metres. The site sits on a steep west-facing slope where the ground drops away towards a stream, and the eastern opening of the horseshoe faces uphill into the slope rather than out towards any obvious viewpoint. A gap in the north-north-west section of the wall may represent the original entrance. The site was compiled by archaeologists Geraldine Stout and Padraig Clancy, whose survey notes provide the basis for what is formally recorded about the structure.

Kilmashogue is accessible from the Dublin Mountains Way and from the car park off the Ballyboden Road, and the general area is well walked. The cashel itself sits on a steep gradient, so the approach involves some careful footing, particularly after rain when the slope can be slippery. Because the enclosure opens eastward rather than outward from the hill, the interior is most legible when approached from below, where the full horseshoe shape becomes apparent against the slope. The stonework is unrestored and reads as a working ruin rather than a managed monument, which means the wall faces are worth examining closely for the construction technique, the alternation of large facing stones and the packed rubble between them.