The tower, with an internal diameter of 7.5 metres and walls roughly 3 metres thick, was constructed from uncoursed limestone with a rubble core bound in lime mortar. What makes this structure particularly intriguing is its unusual external design; rather than a typical circular form, the outer face was built in seven straight sections, creating an almost polygonal appearance. The interior sits about 1.5 metres below the external ground level, suggesting the presence of a semi-basement beneath what would have been the first floor, with evidence of joist holes indicating where wooden floors once divided the internal space.

The keep shows clear signs of sophisticated medieval defensive architecture, including narrow vertical arrow slits positioned at the angles where the straight wall sections meet, and evidence of a wooden hoarding system that once projected from the top of the tower. Square joist holes flanking vertical openings in each wall section reveal where this timber gallery would have provided defenders with an overhanging platform from which to rain missiles down on attackers. The remains of a large first-floor window embrasure, with its segmental arch still partially visible, alongside horizontal coursing at different levels, indicate the tower was constructed in three distinct phases. Though only a section of the curtain wall that once enclosed the summit survives today, early photographs from before its collapse show it standing almost 5 metres high, complete with crenellations and loop-holes.

Shanid’s history stretches back to around 1198 when William de Burgh first occupied the site, though the stone keep likely dates from slightly later. By the mid-13th century, the castle had passed into the hands of the Geraldines, who held it until the late 16th century. A 1583 description paints a melancholy picture of the castle’s decline, noting it was already in ruins, “situated on top of a high mound, and is girded by a barbican, which, with the castle, lately fell.” Today, large fragments of the fallen tower lie on the summit alongside the surviving wall, including a block containing part of a window opening that matches the remaining embrasure, complete with the impression of the wooden plank centring used during its construction.