Churchill War Rooms The Churchill War Rooms is a museum in London and one of the five branches of the Imperial War Museum . The museum comprises the " Cabinet War Rooms " , a historic underground complex that housed a British government command centre throughout the Second World War , and the " Churchill Museum " , a biographical museum exploring the life of British statesman Winston Churchill . Construction of the Cabinet War Rooms , located beneath the Treasury building in the Whitehall area of Westminster , began in 1938 . They became operational in August 1939 , shortly before the outbreak of war in Europe . They remained in operation throughout the Second World War , before being abandoned in August 1945 after the surrender of Japan . After the war the historic value of the Cabinet War Rooms was recognised . Their preservation became the responsibility of the Ministry of Works and later the Department for the Environment , during which time very limited numbers of the public were able to visit by appointment . In the early 1980s the Imperial War Museum was asked to take over the administration of the site , and the Cabinet War Rooms were opened to the public in April 1984 . The museum was reopened in 2005 following a major redevelopment as the Churchill Museum and Cabinet War Rooms , but in 2010 this was shortened to the Churchill War Rooms . Construction . In 1936 the Air Ministry , the British government department responsible for the Royal Air Force , believed that in the event of war enemy aerial bombing of London would cause up to 200 , 000 casualties per week . British government commissions under Warren Fisher and Sir James Rae in 1937 and 1938 considered that key government offices should be dispersed from central London to the suburbs , and non - essential offices to the Midlands or North West . Pending this dispersal , in May 1938 Sir Hastings Ismay , then Deputy Secretary of the Committee of Imperial Defence , ordered an Office of Works survey of Whitehall to identify a suitable site for a temporary emergency government centre . The Office concluded the most suitable site was the basement of the New Public Offices , a government building located on the corner of Horse Guards Road and Great George Street , near Parliament Square . The building now accommodates HM Treasury . Wartime use . During its operational life two of the Cabinet War Rooms were of particular importance . Once operational , the facility ' s Map Room was in constant use and manned around the clock by officers of the Royal Navy , British Army and Royal Air Force . These officers were responsible for producing a daily intelligence summary for the King , Prime Minister and the military Chiefs of Staff . The other key room was the Cabinet Room . Until the opening of the Battle of France , which began on 10 May 1940 , Prime Minister Neville Chamberlain ' s war cabinet met at the War Rooms only once , in October 1939 . Following Winston Churchill ' s appointment as Prime Minister , Churchill visited the Cabinet Room in May 1940 and declared : ' This is the room from which I will direct the war ' . In total 115 Cabinet meetings were held at the Cabinet War Rooms , the last on 28 March 1945 , when the German V - weapon bombing campaign came to an end . On 22 October 1940 , during the Blitz bombing campaign against Britain , it was decided to increase the protection of the Cabinet War Rooms by the installation of a massive layer of concrete known as ' the Slab ' . Up to 5 feet ( 1 . 5 metres ) thick , the Slab was progressively extended and by spring 1941 the increased protection had enabled the Cabinet War Rooms to expand to three times their original size . While the usage of many of the War Rooms ' individual rooms changed over the course of the war , the facility included dormitories for staff , private bedrooms for military officers and senior ministers , and rooms for typists or telephone switchboard operators . Two other notable rooms include the Transatlantic Telephone Room and Churchill ' s office - bedroom . From 1943 , a SIGSALY code - scrambling encrypted telephone was installed in the basement of Selfridges , Oxford Street connected to a similar terminal in the Pentagon building . This enabled Churchill to speak securely with American President Roosevelt in Washington , with the first conference taking place on 15 July 1943 . Later extensions were installed to both 10 Downing Street and the specially constructed Transatlantic Telephone Room within the Cabinet War Rooms . Churchill ' s office - bedroom included BBC broadcasting equipment ; Churchill made four wartime broadcasts from the Cabinet War Rooms . Although the office room was also fitted out as a bedroom , Churchill rarely slept underground , preferring to sleep at 10 Downing Street or the No . 10 Annexe , a flat in the New Public Offices directly above the Cabinet War Rooms . His daughter Mary Soames often slept in the bedroom allocated to Mrs Churchill . Abandonment and preservation . After the end of the war , the Cabinet War Rooms became redundant and were abandoned . Their maintenance became the responsibility of the Ministry of Works . In March 1948 the question of public access to the War Rooms was raised in Parliament and the Minister responsible , Charles Key MP , considered that ' it would not be practicable to throw open for inspection by the general public accommodation which forms part of an office where confidential work is carried on ' . Even so , a tour was organised for journalists on 17 March , with members of the press being welcomed by Lord Ismay and shown around the Rooms by their custodian , Mr . George Rance . While the Rooms were not open to the general public , they could be accessed by appointment , with access being restricted to small groups . Even so , by the 1970s ( with responsibility for the Rooms having passed to the Department for the Environment in 1975 ) tens of thousands of requests to visit the Rooms were being received every year , of which only 5 , 000 were successful . Meanwhile , the atmospheric conditions of the site , being dry and dusty , were having a detrimental effect on the rooms ' furnishings and historic maps and other documents . The prospect was raised of decanting the contents of the Rooms to an established museum , with the National Army Museum and Imperial War Museum being suggested as candidates . In the event , £7 , 000 was secured to conserve the material in situ . Opening and redevelopment . In 1974 the Imperial War Museum was approached by the government and asked to consider taking over the administration of the site . A feasibility study was prepared but came to nothing , the museum feeling it did not have sufficient resources to commit to the War Rooms . In 1981 Prime Minister Margaret Thatcher , known as an admirer of Winston Churchill , expressed the hope that the Rooms could be opened before the next general election . The Imperial War Museum was again approached . Initially still reluctant , the museum ' s trustees decided in January 1982 that the museum would take over the site , on the understanding that the government would make the necessary resources available . The initial costs were to be met by the Department for the Environment , and the War Rooms intended to be self - supporting thereafter . The Rooms were opened to the public by Thatcher on 4 April 1984 , in a ceremony attended by Churchill family members and former Cabinet War Rooms staff . At first the Rooms were administered by the museum on behalf of Department for the Environment ; in 1989 responsibility was transferred to the Imperial War Museum . Following a major expansion in 2003 , a suite of rooms , used as accommodation by Churchill , his wife and close associates , was added to the museum . The restoration of these rooms , which since the war had been stripped out and used for storage , cost £7 . 5 million . In 2005 the War Rooms were rebranded as the Churchill Museum and Cabinet War Rooms , with 850m of the site redeveloped as a biographical museum exploring Churchill ' s life . The museum , the development of which cost a further £6 million raised from private fundraising , makes extensive use of audiovisual technology . The centrepiece is a 15 - metre interactive table that enables visitors to access digitised material , particularly from the Churchill Archives Centre , via an ' electronic filing cabinet ' . The Churchill Museum won the 2006 Council of Europe Museum Prize . During 2009 - 2011 the museum received over 300 , 000 visitors a year . In May 2010 the name of the museum was shortened to Churchill War Rooms . In June 2012 the museum ' s entrance was redesigned . Intended to act as a ' beacon ' for the museum , the new external design included a faceted bronze entranceway , while the interior showed the cleaned and restored Portland stone walls of the Treasury building and Clive Steps . The design was described as ' appropriately martial and bulldog - like ' and as ' a fusion of architecture and sculpture ' .