Saudi Arabia announces plan to build mega-city.

A loud explosion has been heard near Riyadh's airport, with unconfirmed reports saying Saudi Arabia intercepted a ballistic missile from Yemen.
Saudi air defence forces were quoted by broadcaster Al-Arabiya as saying they intercepted the missile north-east of the capital.
A TV channel linked to Houthi rebels in Yemen said the missile was launched at the airport.
Saudi forces have reported shooting down Houthi missiles before.
It is unclear if any damage was caused or if there have been any casualties.
Yemen has been devastated by a war between forces loyal to the internationally-recognised government of President Abdrabbuh Mansour Hadi and those allied to the Houthi rebel movement.
Saudi Arabia is leading a campaign to defeat the Houthis.

Lebanese Prime Minister Saad al-Hariri has resigned, saying in a televised broadcast from Saudi Arabia that he feared for his life, while also fiercely criticising Iran.
He accused Iran of sowing "fear and destruction" in several countries, including Lebanon.
Mr Hariri's father, former prime minister Rafik al-Hariri, was assassinated in 2005.
The Hariri family is close to Saudi Arabia, Iran's regional competitor.
Mr Hariri has been prime minister since December 2016, after previously holding the position between 2009 and 2011.
"We are living in a climate similar to the atmosphere that prevailed before the assassination of martyr Rafik al-Hariri," he said in the broadcast from the Saudi capital Riyadh.
"I have sensed what is being plotted covertly to target my life."
Mr Hariri also attacked the Iran-backed Shia movement Hezbollah, which wields considerable power in Lebanon.
Addressing "Iran and its followers" he said Lebanon would "cut off the hands that wickedly extend into it".
Iran said the resignation would create regional tensions and rejected Mr Hariri's accusations as "unfounded".
Mr Hariri has made several visits in the past few days to Saudi Arabia, whose leadership is strongly opposed to Iran.
His announcement came a day after a meeting in Beirut with Ali Akbar Velayati, an advisor to Iran's Supreme Leader Ayatollah Ali Kahmenei.
Taking up the prime minister's office last year, Mr Hariri promised a "new era for Lebanon" after two years of political deadlock.
The coalition government he led brought together almost all of the main political parties in Lebanon, including Hezbollah.
Rafik al-Hariri was killed by a bomb in 2005 in an attack widely blamed on Hezbollah.
The prime minister's resignation has opened up a chasm of uncertainty in Lebanon.
It's still not clear why he announced his decision in Saudi Arabia - an extraordinary move that left even his own MPs bewildered.
But the move will be seen through the lens of the great Shia-Sunni divide that's fuelling much of the violence across the Middle East.
It's pitted the Sunni power, Saudi Arabia, against the Shia power, Iran - with both sides backing different players to wield influence.
In Lebanon, the Saudis support Mr Hariri while Iran backs the Shia movement, Hezbollah.
In recent years, Lebanon has largely been spared the violence seen elsewhere in the region.
But with this stunning resignation, many Lebanese will now fear that their country is firmly in the crosshairs of the two regional superpowers.

A British man and woman jailed in Dubai for kissing in public have lost their appeal against their conviction.
Ayman Najafi, 24, and Charlotte Adams, 25, were sentenced to a month in prison with subsequent deportation and fined about £200 for drinking alcohol.
The pair were arrested in November after a local woman accused them of breaking the country's decency laws by kissing on the mouth in a restaurant.
Najafi said he was "very disappointed". The pair plan to make a second appeal.
The initial complaint against them was made by a 38-year-old woman who said she was offended by their behaviour at the Jumeirah Beach Residence, where she was dining with her daughter.
The pair's defence lawyers said the woman - who did not appear in court - had not seen the kiss herself, but had been told by her two-year-old child that the girl had seen them kissing.
The defendants also claimed they had merely kissed each other on the cheek, and therefore had not broken any laws.
The BBC's Ben Thompson, at the court, said the judge spoke entirely in Arabic as he quickly dismissed the appeal, saying he upheld the previous sentence.
They were fined 1,000 dirhams, which is about £200. They now have 30 days to appeal.
It was left to the defence lawyer to explain the verdict to Najafi and Adams.