Of Hairy Bottomed Builders and Other Construction-Related Questions

Coming into London Bridge there is a congregation of cranes - they are on the building site close to the London Assembly Building (colloquially known as Ken's House) and they are likely to be building some glass office buildings. But the question that came to mind whilst passing was how do you build a crane? They are huge. They have those massive concrete blocks slotted in the back to balance out the weight of the lifting arm. How did they get those blocks up there? Surely they'd need a crane to lift such weight. Do they build the crane from the ground up, bit by bit? Or do they have an array of ever increasing-in size cranes to build the BIG one? You see, I've never seen a half-built one.

"Do you remember Paul?"
"Paul Booth?"
"Yes, he and his girlfriend were walking under a site like this one day and a piece of scaffolding fell on her head."
"Did she survive?"
"Oh yes, she's still alive. I was just thinking about it because of those planks going up."
"Yes, but better that than a hairy bottomed builder falling on your head."
When I eventually got off the bus, some time after the place where the scaffolders were throwing up their scaffolding (a painter & decorator friend of mine once confided that he was a little intimidated by scaffolders because they were nutters - liked chucking the poles up to one another and working at the fastest speed possible), I was intrigued to find that what I had imagined was going to be a suave Mr Big-alike (a la Sex in the City) and his elderly mother, turned out, in fact, to be a large middle aged posh man in a large herringbone tweed jacket (black and white large checks, rather loud) and his elderly mother.