Kowloon Walled City was a densely populated and largely ungoverned enclave of China within the boundaries of Kowloon City, British Hong Kong. Built as an Imperial Chinese military fort, the walled city became a de jure enclave after the New Territories were leased to the United Kingdom in 1898. Its population increased dramatically after the end of the Japanese occupation of Hong Kong during World War II, attracting mostly refugees fleeing the renewed Chinese Civil War. By 1990, the walled city contained 50,000 residents within its territory of 2.6 hectares (6.4 acres). From the 1950s to the 1970s, it was controlled by local triads and had high rates of prostitution, gambling, and drug abuse.

In January 1987, the Hong Kong government announced plans to demolish the walled city. After an arduous eviction process, and the transfer of de jure sovereignty of the enclave from China to Britain, 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. Some historical artefacts from the walled city, including its yamen building and remnants of its southern gate, have been preserved there.