How high in the sky is the Burj Dubai?

The world's tallest skyscraper has been built. The questions now being asked are: How tall is it and when will it open its doors? But nobody is saying. The delay is beginning to worry investors, who have paid up to $3.5 million for one-bedroom apartments in the building.

Last year, Mohamed Ali Alabbar, chairman of Emaar Properties, which built the Burj Dubai, or Dubai Tower, said that September 2009 was a "possible and reasonable" date for the opening. But then Emaar said that it wasn't happy with the interior design and wanted to change it. Now it's being said that 2 December, United Arab Emirates National Day, is the new deadline.

When finished, the Burj Dubai will have a working population of 35,000 on 160 floors. It will also house a Giorgio Armani hotel with 160 rooms, four swimming pools, a cigar club and a library. Emaar Properties won't disclose the tower's final height until completion, but most estimates put it at 818 metres. Last year, Emaar's rival, Nakheel, said it was planning to build a one-kilometre-tall tower in Dubai.