From Colossal:

For a now out-of-print book titled Kowloon City: An Illustrated Guide, artist Hitomi Terasawa drew a meticulous cross-sectioned rendering of the urban phenomenon to preserve its memory. The massive panorama peers into the compact neighborhood, glimpsing narrow dance halls, laundry dangling from balconies, and entire factories tucked inside cramped quarters.

See the full resolution panorama.