99% Invisible – "Revisiting The 99% Invisible City"
Host: Roman Mars
Guest/Co-author: Kurt Kohlstedt
Date: September 9, 2025
Overview
This episode celebrates the fifth anniversary of The 99% Invisible City, the bestselling book by Roman Mars and Kurt Kohlstedt. Designed as a “field guide to the hidden world of everyday design,” the episode revisits the book’s approach and shares a series of compact urban design stories from downtown Oakland. The hosts also delve into behind-the-scenes details of writing and designing the book, discussing how they selected, developed, and organized material drawn from a decade of the 99PI show and beyond.
Key Discussion Points & Insights
The Book’s Origins and Field Guide Concept
- The book is a curated field guide to city design, focusing on everyday features usually hidden in plain sight.
- The subtitle itself (“A Field Guide to the Hidden World of Everyday Design”) prompted much internal debate—should it be “hidden” or “secret,” “everyday” or “ordinary”?
“It was like hidden versus secret, everyday versus ordinary. Exactly. Oh yeah, that's right. That's right, yeah.” — Kurt Kohlstedt [01:54]
Stories from the Field Guide (Downtown Oakland)
Each feature illustrates how design shapes our environment:
Anchor Plates: Seismic Reinforcements
- Square metal plates on masonry buildings (anchor plates) brace facades against earthquakes, a crucial function in places like Oakland.
- They come in a variety of shapes and can be ornate or plain.
“Whether they look good or not so good, they've got a job to do. And they all look better than the alternative, which would be, of course, a pile of stones or bricks.” — Kurt Kohlstedt [05:09]
Fire Escapes: Evolution and Safety
- Fire escapes, once novel, have mostly been replaced by internal fortified stairs in new buildings—safer and conforming to codes post-tragedies like the Triangle Shirtwaist Factory fire.
- What looks mundane (stairs) often hides a rich, safety-driven design legacy.
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“You could be walking on the great granddaughter of this fire escape every day and not even notice it.” — Roman Mars [07:55]
Hostile Architecture: Defensive Urban Design
- Examples like decorative knobs deter sitting; bike racks are used to prevent tent encampments, blending defensiveness into aesthetics.
- These covert interventions often shift, rather than solve, underlying social issues.
“When you disguise something, you stop conversations from starting around it, right?” — Kurt Kohlstedt [09:38]
Utility Markings: Official Graffiti
- Colorful spray-painted markings on pavement decode the elaborate web of utilities below—historically implemented after disasters to prevent further tragedies.
- Deciphering the colors gives locals “X-ray vision” of the city.
“What I love about all this official graffiti is that for this stretch of concrete, we all have X-ray vision, if we know how to decode it.” — Roman Mars [12:01]
Traffic Calming Devices: Planters and Speed Cushions
- Common features like planters and bollards help slow traffic.
- Speed cushions are an ingenious variant: they let emergency vehicles pass smoothly while slowing normal cars.
“Honestly, it's pretty simple, but I think it's quite ingenious.” — Kurt Kohlstedt [13:39]
Traffic Lights and Manhole Covers: Local Quirks
- Japanese traffic lights are bluish green due to linguistic and regulatory quirks; manhole covers in Japan are highly decorative—an aesthetic public campaign.
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“You could easily spend a good hour marveling at Japanese manhole covers online. In fact, I encourage you to do just that.” — Roman Mars [15:48]
Microwave Relay Towers: Obsolete and Overlooked
- Enormous point-to-point relay towers remain as relics of the 1950s–1980s AT&T transmission era. Once vital, now often invisible amid modern rooftop clutter.
Center Line Stripes: A Mundane Innovation
- The painted center line, now everywhere, began after a Michigan official was inspired by a leaking milk truck—regardless of whether that story is true.
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“Hines certainly left an indelible mark on the world, even if that milk truck story is...bullshit.” — Roman Mars [20:41]
Property Plaques: Invisible Boundaries
- Metal plaques in the sidewalk demarcate public/private property boundaries, preventing “adverse possession” and subtly reinforcing ownership even in apparently public spaces.
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“Once you recognize what these markers signify and start to see them, you'll also start to see open spaces differently...” — Kurt Kohlstedt [23:12]
The Bookmaking Process – Behind The Scenes
Choosing and Organizing Material
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Selection involved massive spreadsheets, rating each story’s “field guide” value and interest.
“If you’re going to write a book, maybe write it about one thing instead of a hundred things.” — Kurt Kohlstedt [28:59]
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Collaboration between Mars as story picker and Kohlstedt as organizer—a productive creative tension.
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They balanced “the best, most interesting stories” with the need for a book that made logical sense.
Adapting Content from Audio to Print
- Writing for a book differs from podcasts—less repetition, more structural coherence, fewer connective “handoff” sentences between stories.
- Their editor, Kate Napolitano, encouraged them to accept that readers can jump around instead of steering them directly.
“Kate was just like, no, people will not read it that way. ... If they're going to read the next one, they're going to read the next one.” — Roman Mars [35:07]
The Timeline and Collaboration
- Making a book is a long process, demanding patience and iterative deadlines.
- Additional challenges involved collaborating intensely with illustrators and designers to ensure the book lived up to the show’s spirit and reputation for design.
Tension and Triumph in Content Choices
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Some stories (like “Standardized Time”) were almost cut—saved only after simplifying and streamlining to highlight their value.
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The last story included involved a San Francisco boulder drama; they fought to add it because it perfectly encapsulated the book’s themes.
“In some ways, some of my favorite pieces are the ones I had to fight for.” — Kurt Kohlstedt [41:58]
Notable Quotes & Memorable Moments
- “The idea was to create a kind of field guide to the city. Not any particular city, but a guide to the underlying design principles of every city.” — Kurt Kohlstedt [01:33]
- “For this stretch of concrete, we all have X-ray vision, if we know how to decode it.” — Roman Mars [12:01]
- “Once it's clear why something is the way it is, people can start to debate whether or not a given design, quote, unquote, solution is humane or equitable or even effective.” — Kurt Kohlstedt [09:52]
- “One of those things that we were really involved in, because one of the pitfalls of having a show about design is that the book you make better be good. You know, it better look good. It better read well. It better flow. It better have a reason for existing.” — Roman Mars [38:45]
Timestamps – Notable Segments
- [01:12] – Introduction of the book and its field guide concept
- [03:16] – Anchor plates & seismic design in Oakland
- [05:33] – Fire escapes: origin, evolution, and legacy
- [08:00] – Hostile architecture & invisible deterrents
- [10:18] – Utility marking colors and their safety function
- [13:00] – Traffic calming: planters, bollards, and speed cushions
- [14:03] – Traffic light colors in Japan and manhole art
- [16:52] – Microwave relay towers: technology relics
- [19:43] – Center lines and their quirky origin story
- [21:50] – Property line plaques and the invisible public/private divide
- [28:35] – Behind the scenes: book development processes
- [35:07] – Editing, pacing, and the difference between podcast and print
- [41:58] – Writers’ favorites and stories that needed fighting for
Tone & Takeaway
True to form, the episode is a mix of affectionate urban geekery, dry humor, and an infectious enthusiasm for overlooked details. The conversation between Roman Mars and Kurt Kohlstedt is warm, teasing, and collaborative, offering listeners both a practical guide for noticing city design and an inspiration for seeing the built world anew. For fans and newcomers alike, this episode is a love letter to the overlooked forces that shape our cities—and a testament to the curiosity and craft behind the 99% Invisible project.