A number of pillboxes 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 approximately 50m north of Citadel North Bastion. The interior is, largely filled with earth, it measures 2.76m by 2.73m and is entered through a doorway, 0.52m wide in the southern side. (location accurate to the nearest 1m based on available information)