Crane Pollution

About a week back a huge crane was built in view of our back garden. How was it built you ask? Why, it was assembled with another crane of course! Explain that, science.

I guess it'll forever be one of those unsolved mysterys, like how do the 'keep off the grass' signs get there, or why does a pair of size ten shoes cost the same as a pair of size eights, regardless of the excess material it took to make them.