HM Naval Base Clyde, commonly known as Faslane, is home to the Royal Navy submarines that carry the UK’s nuclear weapons.
3000 service personnel and 4000 civilian staff are based at the site on the west coast of Scotland.
Faslane first made headlines in 1917 when the steam-propelled HMS K13 sank in the waters of Gare Loch during sea trials.
During the Second World War Faslane developed as a naval base for submarines and ships.
But it was in the Cold War of the 1960s, when Britain decided that submarines carrying nuclear weapons would be its best response to the threat of a Soviet attack, that the base grew into a strategic facility.
HM Naval Base Clyde was opened by HRH The Queen Mother in 1968 and the following year the Royal Navy began Operation Relentless.
It was initially home to the Royal Navy’s Resolution-class submarines, which were part of the Polaris Programme and were first submarines with nuclear capability.
Op Relentless has seen one of four submarines always on patrol, carrying the missiles that is Britain’s nuclear deterrent against an attack.
The Vanguard-class submarines came in during the 1990s and replaced the ageing Resolution subs.
The base has expanded over the decades to accommodate more sophisticated submarines and a growing number of vessels.
The base is only 25 miles from Glasgow and has attracted some controversy during its 50-year history.
The Campaign For Nuclear Disarmament has demonstrated against the Trident fleet and a permanent peace camp was set up outside Faslane in 1982.
The Scottish National Party (SNP) - Scotland's ruling party since 2007 - has also called for the scrapping of the Trident Fleet but said it would retain the base to service conventionally armed and powered naval units.
However, Faslane will see more nuclear-powered submarines stationed here in the next couple of years and all 11 Royal Navy Trident and Attack submarines will be based on the Clyde by 2020.