
if you want to go deep on it this was a great read (Ghetto at the Center of the World):
https://press.uchicago.edu/ucp/books/book/chicago/G/bo112348...
In any case, the closest thing today in Hong Kong to the Walled City is probably Chungking Mansions. Not quite as anarchic or run down, but it does have a family resemblance. I recommend the book Ghetto at the Center of the World: Chungking Mansions, Hong Kong for more about the interesting global mix of people and economics that goes on there.
https://en.wikipedia.org/wiki/Chungking_Mansions
https://www.press.uchicago.edu/ucp/books/book/chicago/G/bo11...
