Kowloon Walled City was a tiny Chinese enclave in Hong Kong.
It was a military fort for hundreds of years, but later became a very dense settlement. In 1980, the city had about 35,000 people on about 20,000 m² of land, making it one of the most densely populated places on earth. It was torn down in 1993, and a park called Kowloon Walled City Park was built in 1994.