Many Chinese cities were walled and fortified, and some of the fortifications were quite large. Pingyao's city wall approached Ninevah's in height. The Forbidden City is effectively a large castle.
But since China usually succeeded in centralizing power, it didn't need as many non-frontier fortifications as the European patchwork of mini-states did--in fact, they would be a risk to the central state. I suspect I'll learn that warlords' castles were dismantled when the new Emperor conquered them.
But there were families with fortified compounds too. There's probably a lot of history in there.