

Illustration by Hitomi Terasawa (寺澤 一美), from Kowloon City: An Illustrated Guide (大図解九龍城) (1997), by the Kowloon City Exploration Team, supervised by Hiroaki Kani (可児 弘明).
Learning about the strange and extraordinary story of Kowloon Walled City feels like it was a rite of passage for my particular flavor of Internet nerd during the late oughts. It lurks in various footnotes as a trivia item, but these fail to convey its truly staggering scope. At its height, its roughly 35,000 inhabitants lived in what is almost certainly the most densely populated living arrangement that human beings have ever experienced in all our history, with about 1.3 human beings per square meter of a surveyor's map. That's over 115 times as dense as habitation in present-day New York City. That's about 29 times as dense as Manila, the world's most densely populated city at the time of this writing.
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