The Walled City Where Sunlight Couldn't Reach - Megacities - io9
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A dystopian megacity, in which buildings merge together to become a
single solid block, is the stuff of science fiction — but it already
happened, in Hong Kong. The Kowloon Walled City was packed so tightly,
it became an arcology.

A dystopian megacity, in which buildings merge together to become a
single solid block, is the stuff of science fiction — but it already
happened, in Hong Kong. The Kowloon Walled City was packed so tightly,
it became an arcology.