I loved this article from the Atlantic by Alexis C. Madrigal:
On the surface of Toronto, the air is cold. Life survives, but in the winter months, it is just barely in the habitable zone.
So, the humans of the city have burrowed underground. It began in the early part of the last century. Then, as the towers of the downtown core exploded upward, the underground labyrinth expanded, tunnels finding each other, the whole thing turning into a four-million-square foot city within a city.
Some 100,000 people regularly commute through this place, including 2,500 people who work down here. There are 1,200 stores. Access to PATH is worth about $2 per square foot to the office owners in the towers above.
Landscape architect Pierre Bélanger describes the system as a set of nodes—shopping pavilions, food courts—connected by axes. And, also like the Internet, it’s a public-feeling space that is actually privately held. Ken Jones, who has studied the retail establishments of the space, describes PATH as “a retailing subsystem that is directly linked to the corporate city of enterprise” that “serves the residents of the white collar city of privilege.”
The most mundane way to think about PATH is that it is simply an “alternative grade” pedestrian walkway. It’s one of about 50 large systems throughout the world.
But I like to think of it as a spaceship underground. After all, the available square footage is greater than the Constitution-class Starship Enterprise from the original Star Trek.
Given the state of the space program, The HMCS PATH is about as close to a spaceship as you’re likely to board in your lifetime. We are talking about a completely climate-stabilized, surveilled, artificially lit human-maintained system.
There are design guidelines that keep things consistent down there. For example, the city of Toronto does not like high lighting-contrast, presumably because it’s disorienting. They, in fact, have an artificial light to darkness ratio that they suggest following: “Avoid glare and/or shadowed areas, and maintain a uniformity ratio that does not exceed 4:1 (i.e. the ratio of average maintained level of illumination to the minimum level of illumination).”
For safety’s sake, they tell architects to avoid blind corners around which one could get jumped. If there are areas that seem dangerous, they ask that for convex mirrors to be installed, not to mention security cameras for low pedestrian flow areas.