The painstaking jacking down method is said to be safer, cleaner and more environmentally-friendly and is being used to clear a skyscraper in Tokyo.

Contractor Taisei Corp is jacking down each floor of  a 40-storey hotel building while keeping the roof on the building.

The demolition technique is being used to remove The Akasaka Grand Prince Hotel over a six-month contract lowering it almost imperceptibly two floors at a time to the ground by a deadline of this May.

It is the second time the technology has been used in Japan.

The large roof section of the building, supported by temporary columns installed within the building, is lowered by jacks.

There is less dust and noise because the work is done in a space enclosed between the roof and scaffolding, Taisei officials said.

The demolition is so gradual that many people in Tokyo’s streets have not even seemed to notice, with one onlooker exclaiming after being told “Really? I didn’t realise”