You will rarely see a building over 20 years old in ANY part of China, they have usually fallen down by then. I have photos of my MiLs apartment block taken in 2011 - built in 1998 - it looked as if it was about to fall down, and it has now been demolished.
"New" apartment and shopping complexes look "old" after about a year; one new shopping complex that was not even finished when I visited in 2008 was already 1/2 empty and semi derelict when I returned in 2011, and my SiLs brand new apartment building in 2011 (again, the top 10 floors werent even finished at the time), looked 10 years old when I went back in 2012.
PS, it wasnt just us forcing "Trade Concessions"' France, Italy and Prussia also had large swathes of mainland China under their control.
PPS, the "One Child" rule only ever affected about 40% of China's population (poor city dwellers and people on the parties $hit list), and "Economic Development Zones" like Shenzhen are entirely exempt.
(That's me with a can of "Pearl River" lager - yummy stuff!!!)