Kowloon Walled City was a settlement in Kowloon, Hong Kong.  

It was condemned and demolished in 1994 due to poor construction standards, not to mention living standards. At its height, Kowloon Walled City had 33,000 residents living in 350 buildings teetering on a plot of land 210 meters by 120 meters. That’s only 2 football fields. 

I noticed this hyper-populated ghetto was surrounded by vacant lots on three sides. This area in Hong Kong had some bizarre zoning laws.