The world's tallest building has been unveiled amongst an impressive show of fireworks, lasers and fountain displays.

The official height of Dubai's Burj Khalifa, previously known as Burj Dubai, was announced yesterday (4 January) as 828m. Developed by Emaar Properties, the building is 320m taller than Taiwan's Taipei 101, which had held the title of the world's tallest building since 2004.

"Thousands of people from more than 100 countries have contributed to the realisation of Burj Khalifa," said Mohamed Alabbar, chairman of Emaar Properties. "The tower embodies the spirit and optimism of global collaboration, and shows to the world what can be achieved when communities work in partnership."

A dramatic sound, light, fireworks and fountain display described the evolution of the tower, and ended in a climax of lasers and fireworks bathing the tower and surrounding area in white light.

Burj Khalilfa comprises luxury residences and offices, the world's first Armani hotel and the world's highest observation deck, located on the tower's 124th floor. The deck, named At the Top, will be officially opened to the public today, January 5, 2010. Around 90 per cent of the tower's offices and apartments have been sold.