Like those huge cranes on the top of buildings that are being constructed - how do they get them up there???
depends on the situation some times they use another crane. some times it is hydralic lifts. they just keep adding sections to the superstructure from the bottom. as they go up they enclose the crane superstructure in side the envelope of the building and add sections of super structure as needed to change the height. then they bolt it back to the building
A combination of methods. Use a helicopter to lift pieces of a small crane to the top of a building and assemble it there. Then use this smaller crane to life pieces of a larger crane to the top of the building for assembly.
With more massive cranes. Sometimes, they will put them up in pieces - and assemble them on top of the building.
They erect it from the bottom and work their way up. The crane is also connected to the building at specific intervals. The larger cranes require a footing to be placed that can be as large or even larger than the building footings. The cranes are disassembled in the reverse order. The top piece is taken off and lowered. Cheers and good luck.
Piece by piece. Kind of like stacking cups.