Watch This When You're High - How Do Tower Cranes Build Themselves?

Looking around the city there are cranes everywhere. And they somehow get taller as the building structure climbs taller so how the hell do they do that? I've always wondered. 

Turns out they build themselves. 

Just another crazy human feat of engineering. 

p.s. - Crane operators have to have some of the coolest/shit your pants scariest stories on the planet. 

Keep suggestions coming. Keep them classy. No butt stuff.