99% Invisible, "Beyond the 99% Invisible City"

Host: Roman Mars
Episode Date: December 30, 2025

Overview

This special episode of 99% Invisible, hosted by Roman Mars with regular contributor Kurt Kohlstedt, invites listeners on a thoughtful journey "beyond" the stories of their hit book The 99% Invisible City. The episode shares four previously unreleased mini-stories, each reflecting the book's central themes: Infrastructure, Urbanism, Geography, and Architecture. Designed as both a celebration of overlooked design and a preview of a forthcoming expanded edition, the episode stitches together fan-fueled story leads, historical rabbit holes, and delightfully quirky details of the built environment.

Key Discussion Points & Insights

1. Behind the Scenes: Narration, Books, and Chapters

(Timestamps 01:02–03:15)

• Roman Mars coaches Kurt on his iconic introduction, highlighting the show's signature tone—part gravitas, part warmth.

  • Notable moment [01:54]: "That's great. I love it. Print it." —Roman Mars

• The hosts reflect on the success and global impact of their book, The 99% Invisible City, and discuss their decision to share four new stories, each tied to a main chapter of the book:

  • Infrastructure, Urbanism, Geography, Architecture

• Each story reflects deep listener engagement and the show's love of uncovering design's hidden stories.

2. Infrastructure: The Surprising History of Stop Signs

(Timestamps 03:17–13:52)

The Story

Prompted by a listener's question about blue stop signs in Hawaii, Kurt explores the evolution and reasoning behind stop sign design.

Insights

• Origins:

  • William Phelps Eno, dubbed "the father of traffic safety," played a pivotal (if often overlooked) role in the development of early traffic systems, advocating for innovations like roundabouts and signage [04:36–06:15].

• Shape Theory:

  • The octagonal stop sign became standard in 1923 via the Mississippi Valley Association of State Highway Departments [08:00].
  • Roman Mars reading NYT excerpt about shape coding: [09:29]

    "The recommendations were based on a simple, albeit not exactly intuitive idea. The more sides a sign has, the higher the danger level it invokes."

• Color Evolution:

  • Initially, stop signs were yellow (better at night, due to limitations in reflective materials) and became standard in red in the 1950s as technology improved [11:26].
  • Red ties in with other "stop" signals, like traffic lights.

• Blue Stop Signs:

  • These are used on private property (e.g., parking lots) to signal they’re not official government signs [12:39], a clever bit of legal and visual distinction.

• Design Legacy:

  • The classic stop sign's combination of shape, word, and color makes it nearly foolproof—even seen from the back, people recognize its message [13:28].

Notable Quote:

• [09:03] Kurt Kohlstedt (on the octagon as “danger” sign):

  “It sounds sort of occult almost. Right. But...the more sides a sign has, the higher the danger level it invokes.”

3. Urbanism: The Miniature Golf Boom in the Great Depression

(Timestamps 14:09–20:40)

The Story

During the pandemic, Kurt researched how disasters change urban life, leading to a discovery: the explosion of miniature golf during the 1930s.

Insights

• Origins & Surge:

  • Mini golf, while not born in the Depression, exploded as city dwellers needed cheap, space-efficient recreation [15:18].
  • Entrepreneurs set up courses in vacant lots, rooftops, and even under billboards to save on lighting costs.

• Innovation Through Scarcity:

  • Scrappy course builders used whatever materials they could find—pipes, rocks, leftover turf—to devise creative, playable environments [17:43–18:39].
  • Some outlandish attractions: trained monkeys that stole golf balls!

• Social Insights:

  • Mini golf provided both an entrepreneurial opportunity and crucial distraction during a bleak economic era.
  • Its ubiquity and fun-loving culture stood in sharp contrast to the tough times.

Notable Quote:

• [17:24] Roman Mars:

  “I love picturing that, people just entrepreneurially setting up a miniature golf course, like a lemonade stand, like, everywhere they can.”

4. Geography: A Perpetually Open U.S.-Canada Border Park

(Timestamps 20:40–27:26)

The Story

Kurt recounts the history and unique legal status of the Peace Arch Park, which straddles the Washington State and British Columbia border.

Insights

• Origins and Symbolism:

  • The Peace Arch, built in the early 1900s, bears the inscription "May these gates never be closed," referencing an 1812-era treaty guaranteeing an open border [21:24].

• Modern Realities:

  • For most of the past century, people could cross freely within the park's bounds [22:20].
  • During the COVID pandemic, the park became a critical meeting point for cross-border families, even enabling binational weddings despite travel restrictions [23:51].

• Legal Quirks:

  • Even amid strict border closures, the park remains open due to treaty obligations; neither country can close it without risking losing territory to the other [25:12].
  • “If Canada broke the treaty...the US could lay claim to parts of Ontario and Quebec. And if America broke it, Canada could get Parts of Maine, Michigan and Wisconsin.” —[26:08] Kurt Kohlstedt

• Local Concerns:

  • Some locals worry about health risks from visitors, but authorities can’t fully close it without breaching international law.

Notable Quote:

• [25:12] Roman Mars:

  “So this is the treaty that you mentioned, dating back to the War of 1812. I mean, that, that thing really has teeth. Like they have to keep the border open in some place.”

5. Architecture: The White, Stepped Roofs of Bermuda

(Timestamps 27:26–34:12)

The Story

Through a listener lead from Bermuda, Kurt uncovers the ingenious design and resilience of the island’s unique white, stepped stone roofs.

Insights

• Hurricane-Ready:

  • After storms in the early 1700s devastated wood-framed buildings, Bermudians built heavy stone houses with steep, sloped roofs to resist hurricane forces [29:04–29:47].

• Water Collection:

  • The signature stair-step design slows rainwater, channeling it to gutters and allowing residents to collect potable water in large cisterns—crucial in a place without natural wells [30:34–31:23].

• Multi-purpose Innovation:

  • Roofs are coated with white lime, which both reflects sunlight and purifies the water [31:23].
  • Each home stores up to 40,000 gallons, ensuring self-sufficiency during storms or droughts.

• Aesthetic and Practical Brilliance:

  • The shimmering visual effect of the white roofs is a point of local pride.
  • Colin Campbell, Bermudian architect:

    “There should be no dark roofs in America. We should all be doing that. It’s just simple science.” [32:46]

• Global Applications:

  • The system is a model for sustainable, resilient design anywhere facing water scarcity or extreme weather.

Notable Quote:

• [33:21] Colin Campbell:

  “As a living human being, one wonders why we're here. I think in Bermuda you can almost figure it out. I'm that close sometimes.”

6. Bonus Shorts: Conspicuous & Inconspicuous City Details

(Timestamps 36:25–41:22)

Trains → Diners

• The classic American diner mimics the layout and construction of train dining cars—long, narrow, and modular—often shipped like railcars to their final destinations. Their unique look is a legacy of efficient prefab design [37:19].

Hidden Wayfinding in Central Park

• The four-digit code on New York’s Central Park lampposts encodes location:
  • First two digits = nearest cross street
  • Last two digits: even = east side, odd = west side; lower = closer to the edge.
• It's a secret system for park employees…but now you know! [39:13–41:04]

Notable Quote:

• [41:04] Roman Mars:

  “Now that you know, you could…spin around with a blindfold on, set off in any direction, find a lamp and know where you are in Central park, which is pretty cool.”

Memorable Quotes & Moments

• "[On stop sign shapes] The more sides a sign has, the higher the danger level it invokes. By the engineer’s reckoning, the circle…screamed danger and was recommended for railroad crossings." —[09:29] Roman Mars
• "What started us down this road was a letter from a fan." —[03:17] Kurt Kohlstedt (on the importance of listener ideas)
• "Mini golf becomes this kind of logical, infill solution in the urban environment, right?" —[15:18] Kurt Kohlstedt
• “[The Peace Arch park]…ends up being this kind of no man's land. And then when they leave, visitors just have to exit back to their country of origin.” —[22:45] Kurt Kohlstedt
• “It's Bermuda, it's family…Everything's two degrees of separation.” —[28:17–28:25] Colin Campbell

Timestamps for Important Segments

• [01:02–03:15] : Introduction, book background, and episode format
• [03:17–13:52] : Infrastructure — Stop signs, their shapes, colors, and history
• [14:09–20:40] : Urbanism — Miniature golf’s Depression-era explosion
• [20:40–27:26] : Geography — Peace Arch Park and international border quirks
• [27:26–34:12] : Architecture — Bermuda’s water-harvesting, hurricane-proof roofs
• [36:25–38:51] : Conspicuous — How train cars inspired diner architecture
• [39:13–41:04] : Inconspicuous — Secret lamppost wayfinding system in Central Park

Tone and Style

The episode maintains the classic 99% Invisible blend of curiosity, warmth, dry wit, and an appreciation for the quietly genius or delightfully odd designs shaping our world. Roman and Kurt’s interplay is both instructive and playful, continually inviting listeners to appreciate the stories woven into ordinary places and objects.

Final Thoughts

Beyond the 99% Invisible City is a love letter to design’s unsung triumphs, urging listeners to “see” and appreciate the infrastructure, inventions, and hacks that quietly enhance daily life. Whether you’re a long-time fan or new to the show, this episode distills the series’ core appeal: storytelling that turns ordinary things into objects of wonder.

For further exploration:

• Check out the original episodes highlighted by Kurt throughout the show: "Highways 101," "War, Famine, Pestilence and Design," "5440 or Fight," "99% Vernacular," "Train Sets," and the Mini Stories compilations ([41:22]).
• More details and links at 99pi.org.