Ever seen a Chinese acrobat build a stack of chairs? Hydraulic jacks, just under the operator's cabin, lift it a few feet, so that more support structure can be built around the top. Then, the jacks are retracted and reattached to the new section. When needed, the process is repeated.
It's lifted in sections I believe. Once they're at their intended vertical height they then start to construct horizontally. Bit like big boys Mechano (not sure if I spelled that correctly).
