Gibraltar: Why 'The Rock' has been disputed by Spain for centuries
There's a lot of chat about Gibraltar after a former Conservative leader appeared to suggest going to war with Spain to defend it.
Michael Howard said the UK would be prepared to defend Gibraltar like it defended the Falkland Islands from Argentina 35 years ago.
The Falklands war with Argentina in 1982 claimed more than 900 lives.
The statement, which he made in several TV interviews, has been criticised as "inflammatory".
Spain has responding by asking why Britain appears to be "losing its cool".
The chances of British military action against Spain are tiny.
Apart from anything else, Spain and the UK are military allies in Nato, which formally commits Britain to defending Spain from aggression, including from - er... Britain.
However, this kind of talk, in the first week of formal Brexit negotiations to leave the EU, seems to suggest a "rock-y" ride ahead.
Did you just make a pun on 'Rock'?
Gibraltar sits on a tall outcrop of limestone near the southern tip of Spain, often referred to as "The Rock".
Foreign Secretary Boris Johnson made exactly the same rock reference in a tweet expressing support for Gibraltar.
Officially, it's a British overseas territory, and has been since it was captured by Anglo-Dutch ships in 1704.
Pretty much ever since, Spain has been arguing that it should be given back the Rock.
Around 30,000 people live there, on a space about two miles around.
It has its own government that makes decisions on everything apart from defence and foreign policy.
Why does Spain want it, and why is the UK so keen to hang on to it?
In part, you can put it down to centuries of history.
Spain has long called Gibraltar "the stone in the shoe" in relations with the UK.
It is strategically important, being at the mouth of the Mediterranean, just 12 miles from the north coast of Africa.
It is home to a UK military base, port and airstrip.
The people of Gibraltar have repeatedly said they should be the ones to decide their own future.
They overwhelmingly rejected the idea of Spain and the UK sharing control over its affairs in a vote in 2002.
In this latest Brexit row, Gibraltar's government says it doesn't want to be used as a "a bargaining chip".
What happens to Gibraltar when the UK leaves the EU?
Ninety-six per cent of people living in Gibraltar voted Remain in last year's EU referendum.
That makes it by far the most pro-EU of any voting area.
However, if the UK leaves the EU, Gibraltar leaves too.
It cannot apply to join on its own without being recognised as a sovereign state.
Online gambling sites, insurers and other financial companies have their headquarters there because it has both low tax rates and access to the EU single market.
Gibraltar's government says Brexit is "disastrous" for the rock's economy because it puts this balance at risk.
Around 10,000 people cross the border with Spain to work every day, which may be affected by tougher border control.
What else do I need to know about the Rock?
It has monkeys.
The Barbary macaques are perhaps some of the rock's most famous residents.
They're supposed to stay high on the rocky outcrop away from where people live, but there have been recent reports of some of them becoming troublesome.
A main road has to be closed to traffic every time a plane lands because it crosses the runway.
The runway also runs the whole width of the peninsula.
Britain has actually invaded Spain from Gibraltar before - by accident
In 2002, 20 heavily armed Royal Marines on a training exercise made a map-reading mistake and stormed a beach in La Linea instead of Gibraltar.
They were "red-faced" and "beat a hasty retreat", according to this BBC News article from the time.
You made it all the way to here without mentioning Dwayne Johnson?
The Rock of Gibraltar: not to be confused with this guy.