The Secret Nuclear Bunker at Kelvedon Hatch, in the Borough of Brentwood in the English county of Essex, is a large underground bunker maintained during the cold war as a potential regional government headquarters. Since being decommissioned in 1992, the bunker has been open to the public as a tourist attraction, with a museum focusing on its cold war history.Building and intended purposeThe bunker was first built as an air defence station as part of the RAF ROTOR air defence project. Upon the demise of the ROTOR SOC the remaining Nuclear Reporting Cell and UKWMO elements were incorporated into a Home Office 'Regional Seat of Government' or RSG. The bunker was able to hold various numbers of military and civilian personnel, the numbers changing over the years as the role of the building changed from SOC to RSG and in its later years; 'Regional Government Headquarters' or RGHQ. In the event of a nuclear strike the RSG / RGHQs etc. would be tasked to organise the survival of the population and continue government operations.HistoryThe Kelvedon Hatch bunker was built in 1952 - 53 as part of ROTOR. ROTOR was a programme to improve and harden Britain's air defence network. It was constructed by Peter Lind & Company of London who still trade today. The bunker was a hardened (three level 'R4') Sector Operations Centre (SOC) for RAF Fighter Command. It was to provide command and control of the London Sector of Fighter Command. During the 1960s, 1970s, 1980s and early into the 1990s, the UK government (Home Office) maintained the bunker as an emergency regional government defence site. Eventually in the early 1990s when nuclear threat was seen as diminished, the bunker was sold back to the family who had owned the land in the 1950s. It is now a Cold War museum and retains many of its original ROTOR and RSG/RGHQ features.