Central Government War Headquarters

The Central Government War Headquarters (CGWHQ) is a 35-acre (14 ha) complex built 120 feet (37 m) underground as the United Kingdom's emergency government war headquarters – the hub of the country's alternative seat of power outside London during a nuclear war or conflict with the Soviet Union. It is in Corsham, Wiltshire, in a former Bath stone quarry known as Spring Quarry, under the present-day MoD Corsham.

Source: Wikipedia — Central Government War Headquarters (CC BY-SA 4.0)