A Chinese company has claimed that they will construct the world's new tallest building, the 838-metre high Sky City skyscraper, by early 2013. Their timeline for the project? Three months.

Extraordinary stories about construction projects in China are nothing new - there's the recently unveiled full-size replica of an Austrian village, and last year's attempted copy of all of downtown Manhattan. This latest project, led by a company called Broad Sustainable Building (BSB), aims to build a structure higher than the world's current tallest building, the Burj Khalifa in Dubai. The 90-day timeline sounds incredibly ambitious, given that it took Dubai more than five years to build the 828-metre Burj Khalifa.

But BSB claims it not only has the construction methods that will allow for completion of the project on time - it also says the building will cost far less than comparable buildings, and will consume only a fifth of the energy required by a conventional building. The total cost of construction is expected to be CA$640 million, while the Burj Khalifa cost CA$1.5 billion, and Shanghai Tower, another skyscraper currently under construction in China, is estimated to cost CA$2.2 billion.

Here's a comparative size chart of the proposed building:

Not everyone is convinced that the project can succeed as described - a public relations officer for Gensler, the company behind the Shanghai Tower, said "Since the project is still pending, we have no comment on [Sky City] - but it's very hard to believe that [BSB] will be able to build an 800-plus-metre skyscraper in [such a short period of time]".

So far, BSB hasn't announced all the details of Sky City, such as what usage it will be zoned for or how long it will take to manufacture all its components. They have said they plan to break ground in November 2012, and that the tower will be completed in January 2013.

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