How to demolish a skyscraper from the bottom up

In Japan, they do things differently, even when it comes to demolition.For example, the Japanese construction firm Kashima, has perfected a technique of demolishing a building floor by floor, starting at the bottom. Yep, that's starting on the ground floor.What they do is replace the building supports on the ground floor with hydraulic jacks and then remove all internal walls, supports and structures. The floors above are left sitting on the hydraulic jacks. When these are then lowered to the ground, workers start on the next floor and so on.This video shows a time lapse record of the demolition of a 20 story office block in Japan.Neat! In more ways than one.