This structure was completely below ground with raised entrances level to the surface. The shelter was aligned north-east to south-west, and, once the shelter was exposed, it could be seen that both entrances were 52cm above the roof of the central chamber. The entrances were sealed by a cap of corrugated iron covered in concrete, which sat on a recessed lip within the entrance walls, 5cm deep at the sides and the entrance and 10cm deep at the chamber end. This appeared to be part of the original construction and is an indication that the shelters had some form of door or hatch. Both entrances were identical in design; each measured 5.55m by 1m in length and had eleven steps leading down to a corridor ending in a recess (87cm deep). The width of this corridor was 70cm, indicating that the walls were 15cm thick. Directly above the recess was a centrally positioned circular hole (10cm in diameter) in the roof. This is interpreted as either an air vent or an exhaust vent for waste gases. The floor was poured concrete with five 60cm by 46cm concrete slabs set into it.
The central chamber externally measured 7.4m by 1.85m by 2.45m high with an internal measurement of 1.54m at its widest point. The chamber was of unpainted concrete and had a bench extending along the external wall on either side. These benches were 46cm high by 35cm deep and were formed of the same concrete as the entire structure. Evidence of shuttering is clear and the principle of the construction technique is similar to that of the shelters on Area C2, although in this instance a different shape was achieved using the same number of facets (fifteen visible above the benches). This produced a narrower, ovoid section compared to the sub-circular cross-section of the shelters in Area C2. Sixteen 60cm by 46cm rectangular slabs extended down the centre of the chamber. Three more exhaust vents were located at equal distances within the roof.
Both the recess and the internal doorways had the remains of iron hinges and the internal door had the remains of an iron latch, indicating that doors were at one time present. Iron hook latches were affixed to the external wall of the entrance approximately 1m off the floor. The structure displayed inverse symmetry. <1>