The Atlantic has a great article up about the massive construction project currently underway, mainly deep underground in New York City. It's been going on for over five years already, and it's truly enormous in scale – yet most people have never heard about it, and most New York residents have never seen any evidence of it.
Being a government project, of course it's massively over-budget and behind schedule. It would be fabulously shocking if not :)
I'm not a fan of big cities in general, and New York is amongst my least favorite. But the sheer scale of this civil engineering project leaves even me with my jaw dropped. Lots more photos at the link; the one below is a custom (and massive!) tunnel-boring machine built for the project.