Location: China
Then: Originally a Chinese fort, it later became a densely populated city with 33,000 residents in 1980, known for its crowded, dirty conditions and lack of sunlight, earning it the nickname 'the city of darkness'.
Why people went there: It was a lawless area popular with criminals and those involved in illegal businesses, as the government did not intervene due to its dangerous and difficult-to-control nature.
Why people left: In 1993, the government forcibly relocated residents and demolished the city.
Now: Only one building and the city gate remain, now part of Kowloon Walled City Park.