It is 80 years since Churchill's secret War Rooms became operational in the lead up to the Second World War.
With rising political tension with Germany in the 1930s, plans for a purpose-built underground bunker were drawn up in spring 1938.
The search for a suitable site began and, on 31 May 1938, Colonel Hastings Ismay confirmed the basement of the Office of Works, between Downing Street and parliament, as the ideal location.
After a year of clearing rooms, sandbagging alcoves, installing telephone lines and strengthening key rooms, the lights were finally switched on in this Central War Room on 27 August 1939.
The site became the nerve centre for gathering military intelligence, with up to 500 people working underground at the height of activity.
Despite Churchill proclaiming it was from these rooms that he would direct the war, living underground did not come naturally to him.
The curator at the Imperial War Museums, James Taylor, said: "He didn't like it, it's basic, not very Churchillian.
"He much preferred his more luxurious accommodation above and Chartwell in Kent.
"During air raids he actually preferred to go up... And watch the air raids as they happened."