After the Japanese invasion of Hong Kong during the Second World War, China reclaimed the rights to Kowloon Walled City, an ex-military fort. As refugees fled to the area, the Walled City became something of a diplomatic no-man's land — neither the Chinese government nor the British colonial administration were willing to intervene. Between 1945 and 1990, the population of the area raised from 2,000 to an estimated 50,000. An interconnected web of 14-story skyscrapers were erected with no input from architects or planners, and the largely triad-controlled city became infamous for lawlessness and squalor. At its peak, the city, which measured just 2.7 hectares (around 290,000 square feet), had a population density of 1.92 million per square kilometer (that's about 4.97 million per square mile)
A fascinating report from the South China Morning Post looks at what life in the Walled City was like, revealing a close-knit, self-sustaining community that loved their home, despite poor living conditions. Eventually demolished in 1993, the city is now a public park, but its ex-residents still have fond memories of their lives in Kowloon Walled City. "Even now, many people stay in touch with each other even though some old friends are overseas," one ex-resident said, "people who lived there were always loyal to each other. In the Walled City, the sunshine always followed the rain."