The 828 metre skyscraper includes residences, offices, a hotel and an observation deck on the 124th floor.
Here's some more information from developers EMAAR:
'Burj Khalifa' is unveiled to the world and its official height is 828 metres
The world's tallest building was unveiled to an estimated crowd of over 400,000 and the world, in a crescendo of fireworks, lasers and fountain displays. The official height of the tower, unveiled as 'Burj Khalifa', was announced as 828 metres (2,716.5 ft).
'Burj Khalifa', developed by Emaar Properties (www.emaar.com), is the world’s tallest building according to the three criteria of the Council on Tall Buildings and Urban Habitat: ‘Height to Architectural Top’, ‘Height To Highest Occupied Floor’, and ‘Height To Tip’.
The tower is 320 metres taller than Taiwan’s Taipei 101, which had held the title of world’s tallest building since 2004, the year when the project was announced.
Mohamed Alabbar, Chairman of Emaar Properties, said that the tower represented a symbol of hope to the Arab world and a shining example of human achievement. “Thousands of people from more than 100 countries have contributed to the realisation of 'Burj Khalifa'. 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, firework and fountain display described the evolution of the tower, and ended in a breathtaking climax of lasers and fireworks, bathing the tower and the surrounding area in white light.
'Burj Khalifa' comprises luxury residences and offices, the world’s first Armani Hotel, and the world’s highest observation deck, ‘At the Top’, which is located on the tower’s 124th floor. Around 90 per cent of the tower’s offices and apartments have been sold.
‘At the Top’ opens officially to the public on January 5. The handover of offices and apartments starts in February, and the Armani Hotel Dubai will be opened by its designer, Giorgio Armani, on March 18.
More than 60 leading consultants including South Korea’s Samsung Corporation and New York-based Turner Construction International realised the design for Burj Khalifa by Chicago-based Skidmore, Owings and Merrill (SOM).