There used to be this place called “The Walled City of Kowloon” which was technically “NOT” owned by either China or Hong Kong. So, people who were either too poor to live in the fancy new apartments, or people on the run or outside the law, or people just into freedom moved there. And lived for generations. It lasted nearly a century and was “There, I fixed it” many many many times over…

http://en.wikipedia.org/wiki/Kowloon_Walled_City

Originally, there was a wall and a temple in the middle, kinda. Then a few high-rise apartments were built, but it would have looked 1/10th as dense. People built up, they built sideways, they built down. The entire area in the middle was ceilinged over and eventually had enough dwellings it’d support it’s own weight without any central beams. In the middle was a Buddhist temple which never saw light for 40 years, it just had lightbulbs dangled down from its pastiched “Sky”, a big net to catch garbage and when it rained outside, the rain filtered down, hissing when a stray drop or two hit the bulbs.

Inside it was a treacherous yet warm maze of residences, Tong headquarters, massage parlors, brothels, stores, restaurants, unlicensed dentists…

But eventually the fascist pigs, of whatever political facade decided they could not anywhere have anyplace people were at least “Free” so they literally took an army to evict everyone then it took years to tear down it was so dense.