How do they get cranes down off really really tall buildings?
It depends on how tall you mean by really tall. As far as a normal tall building goes: they have mobile cranes which can go very high. These are used to erect and dismantle the site cranes at the beginning and end of a job. For really stupidly tall buildings (such as the Burj Dubai being built in Dubai: destined to become the world’s tallest building) then they have to life cranes up bit by bit. I.E. Crane one lifts crane two above it, which lifts crane 1 above it etc. for construction. And then afterwards they take it in turn to lift each other back down the building.
