• Burj Khalifa is the tallest structure ever built
Burj Khalifa - formerly known as Burj Dubai - was unveiled to the world in a spectacular opening ceremony in the financially-troubled emirate.
At 828 metres or 2,717 feet tall, the skyscraper is more than 1,000 feet taller than Taipei 101 in Taiwan, the previous record-holder.
Dubai's hereditary ruler Sheikh Mohammed Bin Rashid Al Maktoum unveiled a plaque at the tower's base, kicking off inaugural festivities that included traditional Gulf Arab dance performances and skydivers landing parachutes emblazoned with the colours of the United Arab Emirates flag near the tower's base.
• Civic leaders in Dubai hope the tower will provide fresh impetus to the financially-troubled emirate's economy
Dubai renamed the building the Burj Khalifa in a surprise move apparently intended to honour the United Arab Emirates' president Sheik Khalifa bin Zayed Al Nahyan who is also emir of Abu Dhabi.