Before the war
After the devastation of the First World War, British planners feared massive casualties from bombing in the opening week of any new conflict. Evacuation options for the prime minister and cabinet were developed through the 1930s — but the concern that Londoners would feel abandoned if government left the city kept the search focused on central London. In June 1938 the choice fell on the New Public Offices building in Whitehall: close to Parliament, with a steel frame and a large basement.
Building the bunker
Through 1938 and 1939 the basement was adapted into meeting rooms for the War Cabinet during air raids, plus a Map Room where military information from across the theatres of war would be collected and updated in real time. In December 1940 a reinforced concrete slab up to three metres thick was installed above the rooms — but a direct hit from anything larger than a 500-pound bomb could still have destroyed everything. Secrecy was the real defence.
Six years underground
The Cabinet War Rooms became fully operational on 27 August 1939 — a week before Britain declared war on Germany. They ran 24 hours a day for six years. Churchill's War Cabinet met here 115 times, most often during the Blitz and the later German V-weapon offensive. Vital information for King George VI, the prime minister and the armed forces was collected in the Map Room, staffed continuously.
The rooms you walk through
The Cabinet Room was laid out for direct confrontation, with the seating arranged so Churchill could face the chiefs of staff across the table. The Map Room was staffed round the clock — the weather boards in the corridor were famously set to "windy" as a running joke during air raids. From Churchill's bedroom he broadcast several wartime speeches. A small unmarked door hid the Transatlantic Telephone Room — a SIGSALY-encrypted line that let Churchill speak securely with President Roosevelt.
The people who worked here
The switchboard operators and typists in the site's Room 60 were civilian women. During the Blitz many slept between shifts in the cramped sub-basement below — nicknamed "the Dock". A small, human trace of the era survives in the exhibits: forgotten sugar cubes found in a wartime staffer's desk drawer long after the war, kept behind as an accidental record of rationing. The IWM oral-history archive includes recollections from typists like Joy Hunter, who worked here as a teenager and later described the long nights when Churchill dictated.
16 August 1945 — and after
On 16 August 1945 the lights in the Map Room were switched off for the first time in six years. The rooms sat untouched for nearly four decades. IWM opened them to the public in 1984. In 2005 HM Queen Elizabeth II opened the adjoining Churchill Museum — the first major museum dedicated to Churchill's life. Today you walk exactly where his war cabinet did.