THE 99% INVISIBLE CITY

A user-friendly guide to all the overlooked things that make urban civilization tick.

If you’re an infrastructure nerd, a reader of David Macauley, Kate Ascher, or Brian Hayes, then you know that under the sidewalks of your town or city lies an endlessly complex world of pipes, cables, wires, and tunnels. If you want to understand the language spoken in that world, then this book is for you. Building from their popular podcast of the same name, Mars and Kohlstedt explore the occult grammar of the city, much of it hiding in plain sight. What are those boxes at eye level that you see on so many buildings? Well, “firefighters essentially have a skeleton key that opens all of the boxes in their area.” Within a “Knox box” is in turn a copy of the master key for any given building. How is it that one can breathe inside New York City’s Holland Tunnel, which burrows under the Hudson River? The authors explain the process and note that when it was built, using air shafts and aboveground ventilation towers, the air quality in the tunnel was better than that out on the street, adding, “to be fair, that is setting quite a low bar.” Numerous other urban elements are grist for the authors’ amiably churning mill: Those metal stars on the fronts of old brick buildings are the ends of truss rods that prevent the walls from sagging; things are named as they are via complex bureaucratic interactions; the pedestrian-friendly city that allows e-scooters becomes less pedestrian-friendly. Mars and Kohlstedt operate without an agenda other than to share their enthusiasm for urban design (“You can learn so much from reading sidewalk markings—especially when they’re spelled right”), and there’s a pleasant and useful lesson on every page.

The ideal companion for city buffs, who’ll come away seeing the streets in an entirely different light.