Chinese firm Broad Sustainable Building (BSB) is working on erecting the world’s tallest skyscraper, the aptly named Sky City, and that too in an insanely-short span of just 90 days!

The 220-storey skyscraper is to be built in the city of Changsha, using energy efficient and cost-effective pre-fabrication methods, in which units of the building are constructed offsite, then assembled like Lego blocks.

To accomplish the magnanimous feat within the 90-day deadline, BSB would need to erect 5 storey’s-a-day. However, that’s not to say it can’t be done. The Chinese firm is already famous for the construction of the 30-storey, T-30 Hotel – a project completed in just 15 days.

Dubai’s Burj Khalifa, which currently stands as the world’s tallest building at 828 metres-high, was built over a five-year period at an eye-watering cost of $1.5 billion. Sky City One, when completed is said will stand at approximately 838 metres tall, and is projected to be completed at a cost of just $628 million, nearly half the price of the Burj.

Not only will the Chinese high-rise contain everything from apartments, schools, and sports courts to offices, restaurants and shops, but it will also reportedly be an eco-friendly skyscraper with LED lighting, an air filtering central vacuum, and insulated multi-layered walls and windows.

According to media reports BSB is confident the structure will be able to withstand fires (for a specific duration) and earthquakes measuring up to 9.0 on the Richter scale. Nevertheless, other architectural experts believe it is dangerous, not to mention impossible, to fully-construct and secure a structure of this magnitude, in such a short period of time.

Whether or not they’re right, remains to be seen…