Kowloon Walled City in Hong Kong was the most densely populated area in the planet, containing 33,000 residents within 6.5 acres (0.03 km2/ 0.01 sq mi).
In January 1987, the Hong Kong government announced plans to demolish the Walled City. After an arduous eviction process, demolition began in March 1993 and was completed in April 1994.
Kowloon Walled City Park opened in December 1995 and occupies the area of the former Walled City.
According to a survey, the Walled City had a population density of approximately 1,255,000/km2 (3,249,000/sq mi) in 1987.
For comparison, Hong Kong as a whole (itself one of the most densely populated areas on earth) had a population density of about 6,700/km2 (17,000/sq mi) as of July 2009.