English Heritage description of this impressively sited fort:
The monument includes Castle Ring, a large univallate hillfort in a naturally strong defensive position on the summit of Oak Hill, a steep sided spur at the north end of Stiperstones. The enclosed area of the hillfort is roughly triangular in plan with maximum internal dimensions of 280m NNE to SSW by 190m transversely giving an internal area of approximately 3.8ha. The artificial defences are designed to enhance the natural strength of the site. The natural hillslopes fall precipitously on all sides except the south, the natural approach along the ridge top. Here the earthworks are at their most elaborate and include a strong cross-ridge rampart 8m wide and 3.5m high with an outer ditch on the south side 5m wide and 1.2m deep set across the narrow neck of the spur. The rampart is interrupted approximately midway along its length by a slightly offset, inturned entrance 6m wide. Around the south east side of the hillfort the already steep natural hillslope has been cut back slightly to form a well defined scarp slope up to 4.8m high. This ends after 260m fading out on the natural slopes around the north eastern tip of the spur. Here the hillfort relies for defence solely on the precipitous nature of the hillslope. Around the west and north west sides the natural hillslope has been cut back to form a scarp slope, up to 4m high with an outer berm or silted ditch averaging 3m wide. There is no visible evidence of habitation in the interior of the hillfort, the surface of which follows the natural contours of the hill, but the buried remains of such features will survive beneath the surface.