This year marks the 300th anniversary of Gibraltar's capture from Spain. But the sovereignty of the Rock, off the coast of southern Spain, remains a highly sensitive and politically contentious issue.
Gibraltar has been of strategic importance historically
Gibraltar may only be 4 sq miles (10 sq km), but historically it has been strategically important as the crossroads of the Mediterranean Sea and the Atlantic Ocean.
It has been besieged 15 times, and derives its name from the invading Arabic leader who captured Spain and Gibraltar in the eighth century.
The Romans coined the phrase "ne plus ultra" - go no further - to refer to the Straits of Gibraltar.
It remained Spanish until 1704, when it was captured during the war of Spanish succession by a combined Anglo-Dutch fleet.
1704 Britain captures Gibraltar from Spain
1713 Spain formally cedes it to Britain
1783 Spain ends four-year siege
1830 Becomes British colony
1967 Residents' referendum rejects Spanish sovereignty
1969 Constitution affirms UK ties but brings self-government
98.97% of Gibraltar's population vote against shared British-Spanish sovereignty
There have been a number of Spanish attempts to retake Gibraltar, most notably in 1779, when Spain began its four-year Great Siege.
But the Rock went on to become a British colony in 1830, having had its British sovereignty formalised in 1713 by the Treaty of Utrecht.
Gibraltar remained of strategic importance during World Wars I and II as a key point in anti-submarine campaigns.
Miles of tunnels and chambers were dug out of the limestone and an underground city, with its own electricity supply, telephone exchanges, frozen meat stores, water distillers, bakery and hospitals, was created.
To this day the Rock remains a British air and naval base.
Its relations with Spain have ebbed and flowed over the years.
Spanish dictator General Franco closed the border with Gibraltar in the 1940s.
Gibraltar's status came under the spotlight again in 1963 before the United Nations Special Committee on Decolonisation,when Spain revived its claim for the sovereignty of the Rock.
Spain increased border restrictions with Gibraltar, closing the frontier and other means of direct communication with the mainland in 1969.
After 16 years of isolation from mainland Spain, the frontier gates were reopened.
Status: British dependent territory
Languages: English (official), Spanish
Self governing except in foreign policy
In 1969, Britain granted Gibraltar a new constitution giving it self government in domestic matters, a legislative council having been introduced in 1950.
But the majority of Gibraltarians want to retain their British status, according to a referendum carried out in November 2002.
Gibraltarians voted overwhelmingly then to reject a proposal for shared UK-Spanish sovereignty over the British overseas territory.
A total of 187 people voted for the move - 17,900 voted against.
The results of the poll, called by Gibraltar's chief minister, Peter Caruana, are not binding on the British, and the argument over this tiny territory continues.
Spain's foreign minister said then the result had no value because it was a "largely virtual" vote based on a hypothetical agreement.
Spain has said full sovereignty is non-negotiable.
UK Foreign Secretary Jack Straw's pronouncement in 2002 that Britain and Spain had reached a "broad agreement" over the Rock's sovereignty prompted widespread protests from Gibraltarians.
And in 2003 an influential group of MPs warned a joint sovereignty deal for Gibraltar was wrong in principle, unenforceable and should be withdrawn.
Instead, the British government should focus on establishing co-operative ties between the Rock and Spain, said the House of Commons Foreign Affairs Committee.
Last summer Prime Minister Tony Blair sought to reassure Gibraltrarians by saying there could be no question of any deal going through without their consent.