A number of pill boxed were constructed across the Western Heights in the 20th century, to cover the approaches to the heights and are generally inter-visible. This is a Type A Quad (of which there are three others). All are constructed in concrete with brick facings inside and out, concrete floors and flat overhanging reinforced concrete roofs. This example is situated south of the Citadel. It measures 2.73m on each internal face and 1.76m high to the present ground level; the walls are 0.6m thick. The doorway in the west wall is 0.7m wide. (location accurate to the nearest 1m based on avialable information)