New York Underground: A Centuries-Old Underworld of Caverns, Squatters, and Unmarked Doors | Vanity Fair

Good long-form underground geekery at Vanity Fair :

Deep below the streets of New York City lie its vital organs—a water
system, subways, railroads, tunnels, sewers, drains, and power and
cable lines—in a vast, three-dimensional tangle. Penetrating this
centuries-old underworld of caverns, squatters, and unmarked doors,
William Langewiesche follows three men who constantly navigate its
dangers: the subway-operations chief who dealt with the devastation of
Hurricane Sandy, the engineer in charge of three underground
mega-projects, and the guy who, well, just loves exploring the dark,
jerry-rigged heart of a great metropolis.

The scale of these works is breathtaking to behold.  I wish everybody had the opportunity to go down inside the roughed out caverns of these massive works before they are made ready for people.  It's like nothing you've ever seen.