Overpopulation at its finest...

Building up and out is generally the reaction to an increasing population. The other option is is building something like this...

Kowloon Walled City
https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjEzRusvrhL3DFSfiz1ZmrPitt6PeOYbLIt5w828QrnKXNsTrBrMbKQ9beH4BmLvj3EAgJ2C2pLHcwg8nbc420ApuIX4aXK0Kno5X74Cooclys7csqDIuqvNCCYelUNalaCzP7vMXChRis/s1600/
kowloon-walled-city21.jpg

This city proves that building on the existing rather than demolishing is not always the correct choice. Despite being a society of a throwaway culture, there needs to be consideration, that some things created in the past aren't always positive. Some things can be fixed, but we need to acknowledge, some are better off starting again. Needless to say, we can continue forward by learning from these mistakes, and hoping in the future, retrofitting will be the way forward rather than demolition, and replacing with something equally disposable.