A large number of tower cranes is a sign of a prosperous city. Tower cranes have concrete blocks on the short end as a counter weight. Assuming they all have the same concrete load, you can estimate the weight of the concrete from the close up picture taken from my hotel window. (Look up the density of concrete and estimate the volume). Then calculate the maximum load that could be held on the far end of one of the cranes in the bottom picture without it tipping over, using the principle of moments.
